Help identify rear axle

[mongo4298]

Hello, original owner of 1970 Chevy K20. I had the specs for the running gear but they have been misplaced. Before I place the truck on the market I want to address a few items that need attention. Pinion seal and differential cover gasket to start. The RPO code label on the glove box says G86 No Spin Rear Axle. The casting number on the differential is 3934665. I cannot find any numbers on the axle tubes. The Cover is 10 bolt. Approx. 13 inch width. The no- spin is a Eaton HO52. It has a 4 speed muncie SM 465 transmission. The front differential is a Dana 44. The transfer case is a NP 205 small cover/3bolts.
There is no tag on the rear cover thanks to the last time I had the gear oil changed.
Our local dealer is of no help so I would appreciate whatever help I can get. Thanks