Hello, just had the same happen to be on got a used diff and I'm about to do the same repair.
What did you seal back the diff with? silicone?

I just used your basic black (oil resistant) gasket seal. In my experience virtually any quality sealant will work if you properly clean the surfaces. The oil is on the thick side, is not under pressure, and the diff housing is extremely rigid and won't flex at all - this would not typically be prone to leaking.

Thanks! last question. When you loosened the 50mm nut did you just use the tension on the trani to counter the 50 mm nut or did you grab the big 12 point flange? i know all the manuals say not to but the diff is garbage at this point anyway.

That sounds like one of those things written in as "best practice".
Seriously, the engine generates 350 lb-ft of torque, how could I or any normal person damage it with hand tools?

True! The 50mm nut came out easy with the right wrench. Thanks for all your help and your write up! I couldn't get the E brake cable out but i just suspended it on a trani stand.
Everything took me 2.5 hours to swap out the diff on a hoist at a friends shop. I would post pics, but there is too much drama on this site for sizing pics from my iPhone 11.

Thanks again!!!

Catastrophic failure of Rear diff and repair DIY
 

Cake walk to resize pics. Use tapattalk and pick one pic as a time. Or make an iCloud album and share the link.

Google photos easily gets iphone photos to the PC. No need to resize. Just save as from the website.