Hey jfrazer22,
First of all welcome to the Bolt, we are glad to have you and hope you enjoy it. I also have a 1959 Chevy Apache 3600. I bought the Truck Operators manual for it. In the manual it says the following for the 1/2 Ton rear axle:
1/2 Ton- The 1/2 ton rear axle is of the semi-floating hypoid gear Hotchkiss drive type. The rear universal joint rear yoke is splined and locked to the pinion shaft. The hypoid drive pinion is mounted on pre-loaded taper roller bearings. The hypoid design ring gear is bolted to the differential case which is mounted on pre-loaded roller bearings. These units together with the 2 differential side and pinion gears are mounted in a differential carrier containing lubrication channels for the pinion bearings. The axle sahfts are splined to the differential side gears. The outer ends of the axle shafts support the weight of the vehicle on roller bearings.
I hope that this information will help you to determine if that rear axle is from a 1959 1/2 Apache, and if you ever need any help with your '59, you can just send me a PM.
Good luck with your truck.
