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LS accessory drive spacing explained

GM used three accessory drive spacings. Your water pump, balancer and brackets must all match. Here is how to tell which one you have, what to check before you buy brackets, and which water pumps fit. Or jump to the spacing picker.

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How we put this guide together

Of the 2,012 LS swap questions we pulled from forum threads, 88 were about the accessory drive and what hangs off it: A/C compressors that hit the frame, truck alternators that won't fit under a low hood, power steering pumps and pulleys, and radiator hoses that won't line up with the water pump. Many of those problems trace back to one fact: GM built LS engines with three different accessory drive spacings, and parts from different spacings don't mix.

Step 1: Find out which spacing your engine has

The spacing is how far forward of the block the belt runs. The three factory versions:

  • Corvette (-1): closest to the block. C5/C6 Corvette, Cadillac CTS-V, Pontiac G8, Chevrolet SS sedan; the ZL1 also uses it.
  • F-body/GTO (-2): in the middle. 1998–2002 Camaro/Firebird LS1 and the Pontiac GTO.
  • Truck (-3): farthest from the block. Gen III and Gen IV trucks and SUVs, plus the 2010–2015 Camaro LS3/L99.

The quickest way to tell is to know where the engine came from. If you bought a junkyard 5.3 out of a Silverado with its accessories still on, it's truck spacing. Look it up in the engine and donor finder if you're not sure what it came out of, or use the accessory spacing picker.

Step 2: Measure if you can't identify it

If the engine came without a history, measure how far the belt sits forward of the block. The three spacings measure:

Spacing Belt position
Corvette (-1) 2-1/8 in.
F-body/GTO (-2) 2-15/16 in.
Truck (-3) 3-11/16 in.
  1. Measure straight out from the front face of the engine block to the center of the belt (or the belt grooves on the crank pulley). The spacing is how far the belt sits from the block, so the block face is the reference.
  2. Match the nearest value. The three spacings sit about 3/4 in. apart (F-body sits about 3/4 in. and truck about 1-1/2 in. ahead of Corvette; the measured belt positions above work out to 13/16 in. and 1-9/16 in.), so a reading within about 1/4 in. of one of them tells you which you have.
  3. If you're between two, recheck the reference point before you order anything. More: how to measure accessory drive spacing, with our measuring diagram.

Step 3: Decide what you need under the hood

A lot of the forum questions come from this stage. Before you buy brackets:

  • Check hood and fender clearance. Truck spacing puts the whole drive farthest forward, and several of the forum questions ask whether a truck drive will fit under a low hood.
  • Decide on A/C now. Where the compressor mounts (high or low) can decide frame, fender and header clearance, so pick an A/C plan before you pick brackets.
  • Plan the radiator hoses. Most LS water pumps have both the inlet and outlet on the passenger side, so LS swap radiators put both ports on the passenger-side tank.

Step 4: Match every part to one spacing

The balancer, water pump, brackets and pulleys all have to be the same spacing, or the belt won't line up. Water pumps are where people get caught:

  • The LS1 water pump is the most flexible. It fits -1 and -2 directly, and -3 with ICT Billet's spacers. It doesn't clear a VVT timing cover.
  • Only two pumps clear a VVT timing cover: the Gen IV truck pump and the LS3/L99 Camaro pump. If your engine has VVT, start there.
  • Truck pumps have a vertical outlet on top, which matters for upper hose routing and hood clearance.

Step 5: Don't forget the steam line

The LS thermostat sits low on the water pump, so the engine needs a steam line to purge trapped air; without it, air pockets can cause hot spots. More: radiator, fans and steam line Most LS swap radiators have a steam port, and adapters let universal radiators work.

Measured spacing values and water pump fitment are in the tables below. If you've found a combination that works in your car and we haven't covered it, tell us.

Spacings and water pumps compared

LS accessory drive spacing: F-body, Corvette/car, truck
SpacingNameFound onMeasurementsNotes
-1CorvetteCorvette (C5/C6), Cadillac CTS-V, Pontiac G8, Chevrolet SS sedan; ZL1 uses Corvette spacing (LSX Concepts)2-1/8 in (LSX Concepts chart; reference point per their diagram)LSA (CTS-V/ZL1) crank pulley adds an 8-rib supercharger drive ahead of the 6-rib accessory drive (LSX Concepts).
-2F-Body / GTO1998–2002 Camaro/Firebird (LS1), Pontiac GTO (LS1/LS2)2-15/16 in (LSX Concepts chart)
-3Truck / Camaro 2010+Gen III & Gen IV trucks and SUVs (Silverado, Sierra, etc.), 2010–2015 Camaro LS3/L993-11/16 in (LSX Concepts chart)Truck belt plane is one rib off the factory 8-rib LSA supercharger drive (LSX Concepts).

Water pumps

PumpOffsetGenOutletVVT clearanceExample partNotes
LS1 water pump-1Gen IIIcar style0ICT WAT200Most flexible: direct fit for -1 and -2; with ICT spacers for -3. Does not clear VVT timing cover.
LS3/LSA/LS7 Corvette pump-1Gen IVcar style0ICT WAT101
Gen III truck pump-3Gen IIIvertical outlet on top0ICT WAT300
Gen IV truck pump-3Gen IVvertical outlet on top1ICT WAT301One of only two pumps that clear a VVT timing cover.
LS3/L99 Camaro pump-3Gen IVoutlet upper driver side1ICT WAT302One of only two pumps that clear a VVT timing cover.
What power steering hoses work with a 2005 5.3 stock pump in an older truck with a metric steering box?
What we recommend

The cheapest fix we recommend is swapping the fitting on the back of the LS pump for one from an older pump whose threads match your steering box. It comes out with a 1-inch wrench; with the fitting, valve and spring from an older pump installed, a standard 1971 C10 power steering line can bolt up with no custom hose. There are two steering-box fitting sizes, changed around 1981, so match the fitting to your box. The second option is building a pressure line from about 2 feet of -6 Teflon-lined stainless braided hose, with a -6 o-ring adapter at the pump and 90-degree fittings at each end, and reusing the return line cut to fit or an 81+ C10 return hose. A used 2005 hose is worth a try, but the stock 05 hose has turned out too long in these swaps.

Check this first:

  • Identify whether your steering box uses the pre- or post-1981 fitting size
  • Confirm fitting threads match on both the pump and box ends before assembly

Careful: A leaking high-pressure steering line can spray fluid onto hot exhaust and cause loss of assist, so check for leaks at full lock.

Check this first

  1. Identify the fitting style on the truck's existing lines (inverted flare vs O-ring) before ordering the pump fitting.
  2. Check the Saginaw box for leaks and play while the system is open.

Try this, then this

  1. Remove the metric O-ring fitting from the LS pump and install the inverted-flare fitting.
  2. Reuse the stock square-body lines and Saginaw box.
  3. Fill, bleed, and check for leaks under lock.

How you know it's fixed

  • No leaks at the pump fitting, quiet steering, no aeration in the reservoir.

Still not fixed?

  • Leak at the pump: the fitting seat style is wrong; pull it and match flare to flare, O-ring to O-ring.

Key numbers

WhatValue
GM steering fitting changeMost of the Saginaw changeovers to the metric O-ring fittings occurred in 1980; inverted flare was used before that.
Adapter-nut method on square-body swapsWith the factory truck LS power steering pump, you just change the adapter nut from an old SAE pump to the new metric pump, then factory-spec power steering lines can be used.
Alternative: pull the fitting from an older pumpYou can pull the inverted-flare fitting out of an earlier 'canned ham' Saginaw pump and use it in place of the O-ring fitting.

Every option we know of

Maker / productPart #FitsPriceWhereStatus / notes
GM / Lee Power Steering
Inverted-flare fitting for Saginaw/TC pump		LS pump to square-body inverted-flare linesabout $10-$20Lee Power Steering / parts storesIn production
Must match seat style exactly
Aftermarket hose shops
Custom PS hoses		Anyabout $40-$80Local hydraulic shop
More expensive than a fitting swap

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: $10-$30 in fittings; an afternoon.

Which A/C compressor bracket lets me keep a low-mount compressor on an LS swap without notching the frame?
What we recommend

We recommend the Dirty Dingo low-mount A/C bracket if you want to keep the compressor down low without notching the frame. It hugs the block: the compressor sits 10-5/8 inches from the crank centerline, compared to 11-3/4 inches for the Alan Grove bracket and 12 inches for the stock LS truck bracket, and that distance is what decides whether the frame needs cutting. The tradeoff is the smaller Sanden SD7B10, which has roughly 85% of the displacement of the Sanden 508, so overdrive it from the damper pulley and pair it with good insulation and a correct condenser and fan. In the builds we've seen, the SD7B10 cools a truck cab fine. Depending on your mounts, the factory truck compressor can clear with no frame cutting at all, so test-fit before you buy anything.

Check this first:

  • Whether your block is iron or aluminum, since bracket bolt holes differ between them
  • Compressor-to-frame clearance with your specific engine mounts
  • That the compressor is overdriven from the damper pulley

Check this first

  1. Check whether the block is iron or aluminum, since bracket bolt holes differ.
  2. Measure compressor-to-frame clearance with the specific engine mounts before buying.
  3. Test-fit the factory truck compressor first; depending on mounts it can clear with no frame cutting at all.

Try this, then this

  1. Test-fit the factory truck compressor with the mounts first.
  2. If it hits, order the Dirty Dingo low-mount kit with the SD7B10.
  3. Overdrive it from the damper pulley and pair with a correct condenser and fan.

How you know it's fixed

  • Compressor clears the frame at full engine movement with the belt routed and tensioned.

Still not fixed?

  • If it still hits, the engine position or mount style is the variable; a high-mount bracket avoids the frame entirely.

Key numbers

WhatValue
Dirty Dingo low-mount clearanceFrom the center of the crank to the furthest outside point measures 10 5/8 inches, which is what decides whether the frame needs cutting.
Required compressorKwik bracket instructions call for the Sanden SD7B10 model 7176 mini-compressor and explicitly say not to use the Sanden 508 style compressor.
Fitting sizesThe SD7B10/7176 flange-mount fittings convert to tube-O style with male #8 3/4-in-16 for the discharge and male #10 7/8-in-14 for the suction side.

Every option we know of

Maker / productPart #FitsPriceWhereStatus / notes
Dirty Dingo
Passenger side low-mount A/C bracket kit with SD7B10 compressor and fittings		DD-LS-SD7B10-LM-KITAll 1997-2015 Gen III/IV LS$468.99 (combo kit)dirtydingo.comIn production
Smaller compressor; pair with good condenser and fan
Kwik Performance
A/C bracket kit (uses Sanden SD7B10/7176, not 508)		K10700LS swaps; check iron vs aluminum blockabout $200-$300 (approximate)kwikperf.comIn production

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: $200-$470 for bracket and compressor; a day to fit.

Which LS accessory drive clears stock inner fenders on a C10 with room for PS pump and Vintage Air?
What we recommend

We recommend Kwik Performance high-mount brackets (available in Corvette spacing), which clear stock C10 inner fenders with room to spare. The Holley accessory drive, at $1000+, only fits after the inner fenders are recessed. The budget route is stock truck accessories with a 2009 Trailblazer water pump and a cheap idler relocator, about $100 total; the Trailblazer pump measures 7 5/8 inches from block face to pulley nose. Setting the engine 3-4 inches rearward helps header, A/C and accessory clearance across the board.

Check this first:

  • Front drive depth against your radiator and fan (Trailblazer pump nose is 7 5/8 inches from the block)
  • Engine position fore/aft before choosing brackets
  • Low-mount A/C compressor clearance to the frame

Check this first

  1. Mock up the stock truck accessories and check frame-rail and inner-fender clearance before buying brackets.

Try this, then this

  1. Test-fit stock truck accessories for clearance.
  2. If they hit, install the Kwik K10611 high-and-tight bracket.
  3. Add the K10780 or K10675 A/C bracket with a Sanden 7176 if running A/C.

How you know it's fixed

  • Belt aligned, no contact with frame or fenders at full lock and full suspension travel.

Still not fixed?

  • Belt squeal or misalignment: recheck bracket spacing and pulley offset.

Every option we know of

Maker / productPart #FitsPriceWhereStatus / notes
Kwik Performance
High & Tight alternator/PS bracket		K10611Truck/SUV 1999-2013 or Camaro 2010-2015 spacingabout $200-$300 (approximate)kwikperf.comIn production
Kwik Performance
High & Tight A/C bracket for Sanden mini		K10780Sanden SD7B10/7176about $150-$200 (approximate)kwikperf.comIn production
Kwik Performance
Wide-mount mini A/C bracket		K10675Sanden SD7B10/7176about $150-$200 (approximate)kwikperf.comIn production
Holley
Complete LS accessory drive system (alternative)		LS swapsabout $1,000+ (recommendation claim; not independently sourced)holley.comIn production
May need inner fender recess per recommendation (unsourced)

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: $200-$500 in brackets; one day.

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