We build a lot of rods from scratch so maybe this tip will help. Bolt a front fender to the cab (which doesn't need to be on the frame) and then use a tire/wheel combo that is going to be on the finished project and just place it in the wheel opening in the position you think looks the best. Now measure from the front cab mount hole straight forward till in line with the center of the mock-up wheel. Now do this same measurement from the cab mount hole on the frame forward and mark the frame rail. This will be the axle centerline that puts the wheel/tire where you thought it looked the best. Also, forget the factory mounting of the rear end because GM mounted it so the rear tires are 1.5 to 2 inches too far forward or at least this is so on the 47-54 AD's.

Evan