RearEnd Upgrade?

[Titus0]

Hi, Im new to 67-72 C10 world and have recently purchased a 1967 C10, 2wd Short Cab. Me and my Dad have slowly been fixing it up and we've ran into a bit of a problem in the rearend department. When we bought the truck we were told it had a 12 bolt out of a chevelle "not sure what year", but were not sure if it is. Ive found a few numbers off of the pumpkin and axles etc, but ive been unable to determine excatly what it came out of. The numbers are as followed. On the driver's side front side of the pumpkin, Gm 53. On the passenger's side front side of the pumpkin, NF3896838. On the axle housing itself, 12345 67890. Could someone please tell me what this rearend is out of or direct me to where i can find out please...