rear end question

[chev-obsession]

i am converting my truck to 5 lug disc in the front and i want 5 lug in the back too... and i have a chance to buy a rear end that came off of a 72 chevy and all i need is the axles to put into my rear end. but i also know another guy that said he has a rear end that came out of a mid 70's pickup and he would most likey give it to me. would the axles out of the mid 70's one fit into my rear end that i have now?

also the rear end out of the mid 70's one came off of a "heavy half" so would there be anything different, like brakes or anything? any input is greatly apperciated!