TIP 1: To hold the shafts so you can remove the nuts on the ends of the input and pinion shafts, lock the transmission in two gears at once. To put the transmission in 2 gears at once: 

a. Start with the selector shafts for 1/2 and 3/4 in neutral. The ends of the shafts will stick out of the intermediate case a little when both are in neutral. "A" is end of the 3/4th gear selector shaft. It's in neutral. 

b. Put the transmission in 2nd gear by gently tapping the end of  the 1/2 selector shaft ("B") with a plastic hammer. In the picture, it has been tapped into gear.

c. Then push on the 5th/reverse slider to engage 5th gear. 5th is the helical gear on the end of the transmission, the other gear is reverse - a straight cut gear.

Picture and tip from Chris Bennet

Interesting note - slider for 5^th/Reverse (Red Arrow) has rounded teeth on the top and flat teeth on bottom. 

Green Arrow - Gear numbers facing up
Blue Arrow is O-ring - replace and lube.

Green Arrow - polished area with gear numbers
Green Arrow - 5^th gear fixed
Red Arrow - Reverse gear fixed

There is a cross pin in the Main Shaft Nut, and a punch set in the Pinion Shaft Nut. Pin pops out, punch set is a PITA.

I used an Impact Wrench to remove Pinion Shaft Nut. I had to re-attach the tranny to the engine to break the Main Shaft Nut.

Pinion shaft nut must be replaced (per factory manual anyway). I butchered mine.

Green Arrow - Main Shaft Nut 118 ft/lbs
Red Arrow - Pinion Shaft Nut 180 ft/lbs

Note the pin sticking out of the fork shaft. This is normal. It pushes the reverse plunger in and out.

Good picture of the Syncro Ring - Green Arrow & Dog Teeth - Red Arrow.

Pinion Shaft nut off, Output shaft nut loose. 5th/Rev slider removed with shift fork. Pull straight up gently on slider making sure that the tang on the shift selector is clear.

Picture of 5th fork out

A good "memory" picture. Pull Spyder off, then Idler gears noting the washer is on top. Next is 5th free gear, Reverse fixed, 5th fixed.

Measure gap between fork and slider for wear. From factory .1 - .3 mm. Replace when greater than .5 mm. Mine was .2 mm

Here the gear housing has been removed. You have to play with the gear selector to clear the housing.

Light blue arrow is 1st free.
Red arrow is 1-2 gear selector fork
Blue arrow is 3rd free
Green arrow is 3-4 gear selector fork
White is 4th free.

Move 1-2 gear selector to neutral (half way between 1st & 2nd)
Move 3-4 gear selector up so that the slider engages third.
Remove 10 nuts and lock washers from the retaining plates.

Place the bell housing face down on a bench, pop it into 3rd gear, remove the 2 détentes that go into the side of the diff housing, wrap your hands around both shafts and shift rods at the same time, and wiggle out the whole works. The trick is to engage 3rd gear. Same for reassemble. John Walker

DO NOT  loosen the shift forks on their shafts during disassembly. This is not necessary. If you loosen the forks you lose the selector fork alignment. You can remove both shafts at once along with the shift forks. I tie a shop rag around all the gears (both shafts) and the shift forks. The rag holds everything together so I can wiggle the shafts out of the case. When you assemble it you should still check the alignment and adjust if necessary.  Chris Bennet

Another memory picture from the back side.

Top view.

Thanks to Chris and John the stack came out without event.

Remember not to lose the thin metal shim that is under the retaining plates.

This is how the roller bearing was pressed off. 

An old wheel bearing race placed on the bearing and a piece of pipe "pressed" it back on. Make sure that your press tool sits on the case of the bearing (part that touches the shaft), NOT THE Cage (part that holds the bearing).

Order off of shaft.

1st gear with dog teeth. The teeth were about 1/2 the size of the new ones.

Remove large C-clip. STOP !!!! Look at the brake band orientation. The long leg is on the left. Thrust block at high noon, Anchor block at 5:00.

Blue arrow is the Thrust Block.
White is the Anchor Block
Green is the brake band.

Used a cold chisel between gear and dog teeth to work teeth ring off the gear.

Heated the new dog teeth ring in front of a propane heater and it dropped on the gear with very little persuasion.

There is a difference between the 1st & 2nd gear syncro ring. First has a grove that runs on the flat surface from end to end.

Bad Dog!! Bad bad dog. No wonder I couldn't down shift into second without a huge crunching noise.

The brake band legs for second gear are equal in length so the above doesn't apply.

"Make sure the bearing cage and inner race turn freely in any gear you pressed new teeth on. The bore can be distorted by the press work, causing future bearing failure." JW

Output shaft with HUGE nut in the vise. This is a punch set nut like the one on the end of the the pinion shaft.  If you take a dremel and cut across the bottom of the metal that has been punched in, the piece falls right out.

To remove the 46mm nut, Eugene @ PP pegged the old clutch to a wall instead of making a tool out of it. 

Sorry about the picture quality. This was DougE's clutch plate. Dremel off the 4 shaft ends that hold the plate together, pull the springs out and install a nut and bolt as seen here. I used a rather large crow bar and the nut gave way without any problem.

JW on Input Shaft Disassembly:

"The best way to disassemble the shafts is to use inertia. Grab it with both hands and knock it on a steel plate repeatedly. The mainshaft takes a bit more effort than the pinion shaft. Put the plate on the ground so it's solid. Don't worry about damaging anything but the plate. The shafts are hardened, the plate is soft. The stack of gears comes right off. No press needed."

Looks like that block has been used a few times.

Holy Cow . . . . JW's method was a piece of cake. 4 wacks on a scrap of granite and everything came loose.

I wrapped a wash cloth around the shaft and Zip tied it to catch the bearing, etc. when it did come loose.

This is third gear. Syncro was worn badly. Teeth were ok, but will be replaced since I have them. The 3/4 slider had some overall wear on the teeth and the grove in the center was more pronounced than the new one.

Green arrow is the Thrust Block
Blue arrow is the Anchor Block
White arrows are the Brake Bands. (3rd & 4th have 2 bands rather than 1).

For this one I put the dog teeth/gear into a vice with protected jaws and closed the vice just enough to support the dog teeth. With an old wheel bearing race I knocked the gear down enough to pry off the dog teeth with 2 screwdrivers.

Here is my tool in reverse. Main shaft is locked in vice so large flange nut (between retaining plate and tool) can be tightened. Torque spec is 115 to 130 ft/lbs.

DO NOT FORGET TO PUNCH SET THE NUT BEFORE GOING TO NEXT STEP.

There are 3 detantes, 2 horizontal (green arrow shows lower of 2) & 1 vertical (Blue arrow). Make sure the vertical one is in between the 2 shift rod holes and that the 2 horizontal ones are pushed back into their bores.

FIRST THING . . .  INSTALL STEEL SHIMS NOW!!

Pop the main shaft into 3rd gear (move slider by hand onto 3rd gear's syncro, line up the gear stacks and install the shift forks. Zip tie around the two stack and one shift shaft.  If you tighten the tie too much the bearings will not line up. At that point the tie can be cut any way.

Jiggle everything (helps to have someone turn the differential) and it will drop in.

Install lock washers and nuts to hold retaining plates down.

Install upper and lower detante springs and nuts.

Tip from JW: Permatex copper head gasket spray
Tip from local wrench: Use Mercedes Benz gray sealant with no gasket. I used this method after having to re-open the case (you will see later, hint: it has something to do with that detent). So far no leaks.

Here is the stack showing good (blue arrow) and bad (green arrow) shift fork alignment for 1/2 (green) and 3/4 (blue). The slider should be half way between the dog teeth of the each gear. Since I did not have the OE alignment tool, I put the case on, installed 5th and reverse as well as the free 5th gear and torqued the nuts at the end of the pinion and main shafts. I could see through the hole in the bottom of the tranny case that 3/4 was right on the money. Couldn't see 1/2 with the case on, but could tell it was off.

Here you can see what 1/2 looks like after adjusting. I used the spider to align the fork.

Note the alignment of the shift rods at the top of the picture. The look like they are one piece of metal.

MAJOR SCREW UP.  WHEN I PULLED THE CASE THE PIN (GREEN ARROW)  PUSHED THE UPPER DETENTE UP INTO THE BORE ABOVE THE 3RD/4TH SHIFT SHAFT (BLUE PILL).  THIS IS BAD. ESPECIALLY WHEN YOU FIND OUT ABOUT IT AFTER THE ENGINE AND TRANNY ARE BACK IN THE CAR.

THE PILL MUST BE PUSHED DOWN TO WHERE THE RED PILL IS BEFORE INSTALLING THE CASE. JUST POP THE CAP (TO LEFT OF BLUE PILL) OFF AND USE A SMALL ALLEN WRENCH TO PUSH THE PILL DOWN WHILE INSTALLING THE CASE.

The roll pin (Lt blue arrow) holds a collar that the pin slides in to push between the bottom and top detentes.

Put on the gasket and slide the shift rod into the case, and then feed the case and rod onto the case studs at the same time.