How do I find a driveshaft that fits a 5.3/4L60E LS swap in a 60s C10?

Measure your truck and order a custom length; swap combinations rarely match a stock shaft.

How to measure (Speedway's method):

1. Put the rear axle at ride height — not hanging with the car in the air.
2. Measure from the flat face of the rear yoke (the center of the U-joint once installed)…
3. …to the seal surface on the back of the transmission tailshaft housing — not to the end of the output shaft, which makes the number come out short.
4. That one number, plus the correct front yoke and U-joints, is what a custom driveshaft is built to.

Yoke: a 4L60E uses the GM 27-spline slip yoke. Speedway's custom-length kits are rated up to 400 hp (small kit), 600 hp (3 in steel kits) and 1,200 hp (chromoly).

For reference, Speedway's '68 C10 with a 5.3 and TKX manual measured 59-1/2 in (seal surface to rear U-joint center), but your number depends on the engine mounts, transmission and rear suspension.