12 bolt rear end help.

[71ChevyCheyenne]

Hi I have 1971 chevy c10 that im trying to put a new rear end into. The rear end in it right now is a limited slip 4.10 rear end that is shot. Today I picked up a posi 12 bolt from a 67-69 i think. The rear end i have is a 5 lug. The posi is 6. The width is about an inch apart. I was wondering if I could take the whole internals of the posi and swap it into the 5 lug (if the splines on the axles are the same). Any help would be greatly appreciated.