I would take the measurements of the existing rear..distance between the spring perches..over all length of the rear end..and then go off to my friendly local wrecking yards in search of a rear end from a late ford.. find one with a 9"
Just the ususal hardship here..get the pinion angle right and the new one centered and square in the chassis so we do not have a dog walker..might even find one that has the same bolt pattern on the wheels so that does not need changing..
Probably will need some new spring perches welded on..I don't seem to get that lucky to find one tha tis a straight bolt in deal..might have to do something with the shock mounts as well..those never seem to be in the right spot..
Most of the guys I know in the yards are pretty helpful and if they are not go somewhere else..
This is one of the swaps that is really straight forward..and I am assuming this thing is a half ton truck..imp:
the axles from 1957 to 1972 F100's are all Ford 9" rear ends, these are super easy to get anything for(replacement parts, disk brake kits, different 3rd members with better gears and limited slips can be found at a junkyard). I imagine the axles from 53 - 56 would work but I would prefer the 9".
Did you mean, will the newer axles fit into a 53 -56? YES. same srping perch width.