10 bolt help. Please

[57 Chevy 3100]

Question 1) I recently purchased a 1957 Chevy 3100 that already had some modifications done one of which is the rear axle was replaced however besides it being a 10 bolt I cannot seem to identify any other important info I will need when replacing parts. I have attached a photo of the casting number and differential cover. Some of the other numbers on the outside are: GM30, i4056251 (may not be 100%) QP175 (may not be 100%)

Question 2) Upon returning home with the new truck and parking it in the garage I noticed some kind of oil on the floor at first I thought the master cylinder was leaking so I took off the wheel and drum brake cover only to see the master cylinder was bond dry however the oil seemed to be coming from a bearing like thing behind the wheel hub I attached a photo with an arrow pointing to the area. Depending the answer to the first question what would the replacement part be for this also what is all entailed in replacing this part?

Thank you for your help in advance!!!

[57 Chevy 3100]

Some extra photos of the other numbers found.

[monzaz]

The rear end is a 10 bolt 8.5 Corporate rear end used from 1974-2014 trucks and 1970-1996 in GM cars and trucks

If you use 1/2 truck from 1980 it will have all the parts you need

Axle bearing / Wheel seal will be what you need to repair the leak. It will require you to remove the rear cover and pull the axle shaft from the inner part of the rear.

Retaining bolt that holds the pinion cross shaft in that the small spider/ pinion gears spin on.
You will slide this cross shaft (.795) diameter out and push the axle into the housing and then the c-clip can be removed or it will just plain fall out depending on how dirty the oil is.

After the c-clip is removed the axle will pull out easy and you can remove the seal pressed into the housing end.

seal 8835 part number

[57 Chevy 3100]

That is exactly the information I needed. Thank you for your knowledge!