1972 Chevrolet C-10 - Simple C-10 Solutions - Tech

From below, we can see there is ample clearance between the deep PML cover and the Trac Bar. Notice the handy drain plug in the diff cover.

To help finish off the rearend refresh once and for all, we also picked up CPP's rear shock relocation kit. When you lower the rear of the '67-72 Chevys, the rear shock angle become too steep, and this kit helps correct it.

The trickiest part of installing the shock relocation kit is removing the stock upper shock mounts, which are riveted to a crossmember. Use a drill, air chisel, or whatever your preferred method is, but just be careful.

The new upper mounts bolt into the stock rivet holes and come complete with hardware. Just be sure to install the bolt next to the shock from the bottom or the bolt will hang down and prevent the shock from going into place.

The CPP lower shock mounts do the same as the top, but in the opposite direction. They move the bottom of the shock forward another inch or so.

The new upper mounts bolt into the stock rivet holes and come complete with hardware. Just be sure to install the bolt next to the shock from the bottom or the bolt will hang down and prevent the shock from going into place.

Because all these related pieces needed to come apart to install the Deluxe Trac Bar kit, it makes it a perfect time to install the new U-bolts and rear shock relocation kit. The lower shock mounts go in the stock location under the trailing arms, with the shocks facing forward.

Last month, Unitrax changed the ring-and-pinion ratio in the 12-bolt from a 3.73:1 to a 3.42:1 with parts from Randy's Ring & Pinion during its rebuild. This meant the speedometer had to be recalibrated since it was reading 10-15 mph slow. This seemed like it would be a fairly easy thing to accomplish since all that needs to be replaced is the speedometer drive gear in the transmission that's easily accessible. Well, I soon found out the local transmission shops won't sell parts, and trying to tell the kid at the big auto parts chain store that I have a '72 C-10 with a 4L60 tranny in it and I just need a speedo gear was futile. Then the light went on-we got the transmission from Gear Star; we'll call them. We told them the tranny, rearend ratio, and rear tire size, and that we had a 42-tooth speedo gear in there now, and they figured out that we needed to swap it out for one with 37 teeth.

Along with the new 37-tooth speedo drive gear, Gear Star also had the housing to match. There are numbers on the outside of each housing that show which gears they can be used for, and it's important to make sure they correspond properly. The one on the left came out of our tranny and is good for 43-40 tooth gears, while the new one handles 39-36 tooth gears.