I recently got a 55 series 2 chevy truck that has had a later model 10 bolt rear end installed and flipped rear leafs .I was checking and the as in many 10 bolts the yoke is not centered .When checking the rear is 1/4 " more to one side .Is this within normal realms to adapt that rear to the stock frame .My friends say yes but just wanted to get some other opinions .
Off per measurements with the fenders or off per measurements on the frame? If one tire is 1/4 inch closer to the fender than the other it may be a combination of things. Even now it could be that your spring bushings are a bit worn, that the guy who installed the rear end actually did measure wrong or that your reference points don't jive quite right. I'd get my buddy to drive it down a straight street or road while I followed it and see if it looks like it tracks right or if it wants to go sideways a bit. If it drives straight I wouldn't get too worried.