First determine what rear end is in your car. Maybe you already have an 8 1/4 rear.
the one on the yard car is a 8 1/4” that’s valuable. But you shouldn’t of took the axles out of it. Just take it as a complete unit: drum to drum AND take the shock plates and u-bolts.
The differential was disassembled as shown in the pics (did someone need a specific part from it? or were they trying to confirm size?); so, it was already on the ground--another reason I ask if I should take it--it's removed already.