the 6 bolt pattern is 6 x 5 1/2 which is the bolt patter on all chevy/gmc pickups that have 6 bolt rims and it would be any axle out of a 1/2 ton 2wd (1970 and older) or any 1/2 ton 4wd i'd sugest getting a rear end out of a 1973-1987 4wd 1/2 cause they're is plenty out there for the two axles used in the those year (corp 12 bolt and corp 10 bolt)


Link to my photobucket for pics of my vehicles
http://s238.photobucket.com/albums/ff17/OldIronChevy/