Thanks Verdoro, I finally figured it out. I just ran it a few miles up and down the road after the change to RP synchromax, definitely much smoother and slicker shifts. I like it a lot better. Seems a little quieter too, but that might be wishful thinking on my part.
The differential is on tomorrow's list. One more question on that: The tech at RP said I don't need to add a friction modifier, it's already in the RP Maxgear 75-140. I've read a bunch of posts on the subject, some people add an additive anyhow and some don't... which is it? If it's already in there, adding more would give it too much wouldn't it? Thanks again!