SETUP: I use a 4-foot length of 2×12 with a 3/4 hole bored into the middle of it as a work stand. The hole is for the input shaft which protrudes slightly from the bellhousing.
1) With the trans standing on it’s bellhousing and with the tail shaft housing removed, I use either a mototool or a “cape chisel” to remove the “staked” portions of the two nuts on the tail shaft and countershaft.
2) Now lock the transmission in two gears at the same time (With the top cover off, push both the 1-2 and 3-4 synchro collars “down”)
3) Using the two LONG bellhousing bolts at the 10-O’clock and 3-O’clock positions (to prevent the transmission from rotating), use a pipe wrench to remove the main shaft nut.
4) If you don’t have a pipe wrench, use a large chisel against the flats of the nut to drive it off (the nut is not re-usable anyway).
5) Repeat the procedure for the countershaft nut, though for that you may actually have the 30mm socket you’ll need.
6) Now, flip the transmission bellhousing up (a garbage pail half filled with paper makes a nice work stand) and remove the front bearing retainer.
7) Remove the transmission from the garbage pail and put it back on the wood block.
8) Using a pry bar to apply upwards force on the rear bearing, strike the end of the output shaft with a brass or lead hammer.
9) Rotate the shaft between blows until you get the bearing off.
10) At this point, it’s all 12mm socket work and simply disassembling things in sequence, but will generally get you into whatever parts you have screwed up.
If there are any questions, ask them and I’ll revise this as needed…