I'm sure this info is out there somewhere, but if someone can actually put a tape measure on one, I'd appreciate it. I'm looking for '47-'54 Chevy-GMC front axle, and 2WD S10 rear axle spring perch measurements for the Corvair race car project. http://www.jalopyjournal.com/forum/showthread.php?p=5872648#post5872648
Just measured some in my shop for you... 7.5" S-10 Rear Measures 38.25" from centers of spring saddles. Saddles are 2.5" wide. 8.5" S-10 Rear should be the same since they used the same springs. 1951 Chevy Front Axle is 26.75" from centers of spring saddles. I think 40-55 is the same width.