rear axle swap
 

Will the rear axle from a 68 gmc 4x2 fit my 4x4 72 blazer?They both have 6 lugs and leaf springs. Can I use the axles if I have a bad one on the 72? Thanks,moodyholler

If you have access to both axles just use a tape measure measure the width of each and make sure use use the same refrence point on both i.e. outside drum to outside drum or backplate to backplate. Also make sure the spring pads are the same width if not you will have to ground them off and weld new ones on after the axle is in place and the pinion angle is set. Even if they are an in or 2 off you can adjust with wheel back spacing to get your tires to fit right but both axles should be the same.

axle swap
 

I believe the 68 axle will be shorter than your 72. Also, the spring pad width on a 2wd is actually wider than on a 4wd because 2wd frames get wider at the rear axle. You'd have to relocate your spring pads and shock mounts on the 68 axle to make it work in your 72 and then you'd still have a more narrow axle than what you started with.