64 c10 bare rear end.

[D-man313]

I just picked up a 64 fleetside shortbed project. The rear end housing has been sandblasted and painted by the PO. It is just the bare housing, No internals. What would I have to do to get 5X4 and 3/4 Bolt pattern axles with say a 3.73 posi center section? Can I go to the local junkyard and pull the axles and center section out of something with a 12 bolt the same width? Order something aftermarket? Are all 12 bolt housings the same? All 12 bolt centers the same? Where would I measure from to get an idea of what I need to look for at the junk yard?

Thanks
David