What are you using for 8 3/4 pinion seal?

I wouldn't use a leather one for one simple reason. There's no telling how long they've been on the shelf and they are probably dried out. Modern rubber seals are simply light years ahead. Get this one and be did wif all dat, yo.
https://www.doctordiff.com/8-3-4-pinion-seal.html?variation_id=229