MUA5 Transmission to Transfer Case Seal and Synchro questions

Hello Gentleman.

First time post here. I've been lurking quite a long time as I purchased a very clean 2002 Trooper limited with a dead 4L30E for next to nothing about a year ago. I did a good bit of reading on 4L30e problems and repairs hoping it was repairable but full well knowing I might be pulling it out. And if I was pulling it out, well... a 5 speed was going to be going in in its place. After lots of reading here and finding a promising 5 speed from a 98 3.2L amigo I found at a yard nearby... Suffice it to say I've embarked on the 2nd option.

I genetically inherited the "while you're in there" disease from my father and decided to take a crack at installing the Revolution Gear 3:1 low gears in addition to doing the engine's rear main seal, and the front output shaft seal cough "while I'm in there." Upon reading as many forums as I could about the process I've stumbled across a few forums mentioning the seal between the transmission and T case failing and letting all the trans fluid leak into the T case. At the moment have the T case completely stripped down and ready to clean and reassemble with the new Low gears. My "while I'm in there" disease is screaming at me and telling me to replace this seal between the Trans and T case since I am literally able to lay eyes and hands on it as we speak. However I can't find any info on a part number. Just the mention of a mystical forum member named "Jerry" mentioned here.

Does anyone have any Intel or P/N on this seal or know who said "Jerry" is? With 140k miles on the clock of the 98 amigo donor I'd love to freshen up anything that is cheap and easy, like this seal.

Additionally another puzzle; while looking as photos from forums documenting the 3:1 gear swap I noticed something. The dog-toothed gear (I don't know the correct term, please educate) that sets on the top of the shaft (engages low range gears) that comes in from the transmission has 3 blank slots where some small keys COULD sit. (mine pictured below)



I say could because I did have them on the same dog-toothed gear that sits on the 3'rd shaft that engages the front output for 4wd along with some kind of synchro mechanism. (mine pictured Below with keys removed)




On Revolution Gear's own ebay listing there's a shot of a transfer case that Doesn't have them on the primary input shaft (like mine). And another shot of one that does with the addition of some kind of brass toothed plate. (photos of both below).



I guess what I'm asking is, is it ok that mine lacks all that? Did some T cases have synced 4wd engage and others didn't? Additionally do I have the option of putting in a synchro'ed 4wd lock if I source such parts. I'm not that interested in upgrading unless someone on here convinces me, I'm just looking to put my mind at ease that someone hasn't been in here before and left some parts out before I reassemble.

Thank you for your time, wisdom and intel. I've really appreciated this community at a distance and am excited to finally engage with y'all.

-Peace