72 rear end question (12 bolt)

[orngsikL]

'72 c-10 swb coil rear.

ok. so i've got my rear end cleaned up and primed. I pulled the cover off the other day and didn't find any chunks or metal shavings and all the teeth look good. I'm thinking about changing all the bearing and seals. I don't know much about rear ends. How hard is this project? Should I really need to do it?

How many people actually redo all of this with a build vs refilling with gear oil and keep going?

also. it's a 12-bolt and how do I determine ring size?

also there's two little bubbles on the rear end housing facing the sky one is right under the bolt that attaches the panhard to the axel. Well I was trying to unbolt the panhard and the socket cracked that bubble open. I looked inside of it and didn't see anything so I welded it back up...

what gear oil goes back in?