differential rebuild parts

[xp190]

I was wondering where one might be able to obtain parts to rebuild a differential other then from the dealer. I have not seen them listed anywhere on fastlane or any other parts page and I think I should rebuild mine, or at least change the bearings and seals, it whines a lot. I think what I'll do is get a used one for the time being and when I figure out how to rebuild it, rebuild the better one and keep it. Anyone have any better suggestions?

btw it's a 85 190E

xp