Ok, I've been reading the manual pictures that Chris provided. What I don't read or see is how the top shaft (bevel) that the 608 gear is on works. When I spin a rear wheel, the 608 gear doesn't turn but the shaft AFT of the bearing that is just in front of the 621 gear does. If you look at the photo I posted that shows the welded threaded shaft to the bearing race, the shaft through the bearing is what spins. The small gear (and forward) of the 608 does not. 

Is the bevel shaft one piece that goes through all the way? I'm probably sounding like the tractor village transmission idiot, but I'm learning with your guy's help. (I'm an aircraft mechanic by day... tractor nut when I can be)

I plan to split the tractor tonight. I'll post up some more pictures. Old tractors sure are fun!