That rear end looks similar to a 12 bole I have out of a '65 big block Impala. Look on the front side of the passenger side axle tube for a series of numbers and letters just above center usually but should be there under all the crude, dirt, etc. If it is a car rear I can help if U send the numbers/letters.
P.S. I have a '79 Camaro Z28 big 10 bolt 3.42 in my 1st series '55 with a 700R4 - works great though the 275R60s I had on 8" ralleys rubbed a little so went to a 255R60.
