Rear axle identification and info?

[supertrooper]

I have a 1967 GMC 930, 2 wheel drive, dump truck. The rear axle cover has 10 bolts and the cover is completely round. The axles are floating.

Would anyone be able to tell me the model number of this rear axle? I cannot see a tag anywhere on the rear end.

I also need a new rear bearing nut retainer (I think thats what it is called). The thing that you bend the tabs in to prevent the nut from coming loose. At the local dealership it seems that this truck is too old. The guy at the service counter pulled out some old books. There are 2 different kinds he would have to order. Any ideas on where I can order these?

Also, I snapped the right side axle (for the second time now), are the left and right axles interchangeable?

Thanks to whoever can help.