MC...so I don't have to remove the cylinder head, cylinder and cam shaft tensioner per the service manual?...I haven't found a really good process in any post yet.
I was thinking when i wrote that "no" that the Clymer manual probably says you do. I have a Clymer manual copyright 1972 that says you have to remove the starter motor to remove the cylinder head. This is corrected in my 1977 manual.
I will affirmatively say "no" you do not have to remove the any part of the top end to service the transmission.
You would remove the engine. While on the floor, remove all the case bolts that would hold the lower half to the upper half. Mostly 6mm bolts (with 10mm heads) including a pair in the countershaft sprocket area.
Flip it over on the work bench so you are looking at the oil pan. It will be resting on the cam cover and the rear upper motor mount. Remove all the engine side covers. Under the shifter cover, there is a transmission bearing carrier mount which straddles the seam of the 2 cases. It will be obvious. All the shift linkage and this carrier must come off.
Remove the remaining bolts that hold the lower case to the upper case. You must remove the Main Bolts as well, I think i've been told to leave them for last and replace them first.
Might as well take the oil pan off and inspect the oil pump screen.
Then you can crack the cases, with a mallet rap it and you should hear the tone change when its ready to come off. Have a place ready for it. Lift it off. Part of the tranny comes with it, shift drum and forks, maybe more. The heavy stuff, main shaft, stays with the upper case IIRC. Set it aside.
Then go to town.
Anyone else, please chime in. Its been a while for me.