If you look it up in the Chevrolet Truck Repair manual, The specs are in there, and it tells you where to measure. The rear gap is real close to 3/4" , measured between the rear cab support bracket flange which is spot welded to the floor, and the frame.
I always put a piece of 3/4" board between the rear support bracket and the frame with the rear shackle mounts loosely bolted in place, then set the gaps at the front mounts and tighten the front mount bolts tight.
Then I go back to the rear mounts and set those gaps and tighten them up.
The reason being is that without the front mounts secured and shimmed correctly, the rear shackle mounts get wonky side to side, giving you false measurements.
Last edited by 52Carl; 07/02/2023 12:19 AM.
