6L80 swap behind an LS

The 6L80 (and 6L90) is GM's 6-speed automatic, and it's a common swap behind LS engines from 2007+ trucks and Camaros. It uses the GM LS-family bellhousing pattern.

Controlling it: it's fully electronic, so plan the controller first:

• Factory GM ECU/TCM from a donor where it was paired with the engine, tuned for your swap, or
• Holley Terminator X Max with the 558-499 6L80/6L90 transmission kit (Holley's V3 software adds 6L80/6L90 control through that separate harness kit).

Torque capacity: published figures for the 6L80/6L90 are listed on different bases, and we haven't confirmed a like-for-like rating yet, so we don't quote one here. Check the rating for your exact unit with GM or your transmission builder before planning big power.

6L80 vs 4L80E: six gears vs four; both are electronically controlled, and the Terminator X Max handles the 4L80E natively but needs the add-on kit for the 6L80. See both in the transmission guide.