been there, done that, got the t-shirt, sold the rights to the movie.... my absolute worse was cleaning up after the (what I thought) was successful test drive of a transfer case and transmission reseal to find a needle bearing... I thought they looked a bit loose when I put it together; but I was so careful (so I thought) to keep everything in order and where they belonged that I simply dismissed it...
with that said, I blame my brother, I was working on it in my dad's shop and while it was down, he borrowed a tire to fix a flat on his truck. He didn't tighten the lug nuts so as I'm driving the fj40 (to its new owner, lol) the tire came off (no harm other than a bit of scraping on the backing plate)... thus, he must have been also responsible for that needle bearing. In case you're curious.... I never did put it back, and to my knowledge now 20 years later (I saw it when I was in Portland on Thursday), it's still running and driving that way. That said, I think you need that bit in yours