Oh trust me. I have fought that bearing before. LOL. It's a 2 piece needle bearing, so keeping the 2 halves of them lined up, along with "spread open" in that housing to get the inner part of the shaft to slide in, is the trick. Grease is definitely the answer, at least in my book. In your picture, at the very tip of your arrow, that center circle thing is just a little metal oil deflector/washer. It shouldn't move at all either way. In short, if you ever half any type of bearing that won't stay in place during assembly, try some grease. Auto transmissions have a few of those "flat" type needle bearings, and those are notorious for making your life hell. Ha Ha!
As far as replacing all of the seals, you can never go wrong with new ones, unless you install them incorrectly, which does happen. For my truck, I think I am just going to go with the front output (which can suck to install since the cross member is in the way), the rear output, and the actuator seal and call it a day. I've never actually seen an input seal leak on one of these. I used to see a lot of them on the on Land Cruisers though. Pull the fill plug on the t-case, and if it starts pouring out, you know you have a problem. LOL. Which also means your trans is probably fairly low on fluid.
Anyway, this is a great topic and thank you for chatting. Let me know if you have any other questions, or if you see any other concerns.
