I am looking for a 1983 pontiac acadian diesel isuzu transmission manual 5 speed

Jeeps have an ECM ( Electronic Control Module) on the transmissions as well as the engine.

it is driven by a drive gear on the output shaft of the transmission. you could have a bad driven gear that is the gear that is driven to create the electrical pulses to show a speed. the drive gear on some transmissions are part of the output shaft and some gears are replaceable without replacing the output shaft. in either case a part can be replaced without replacing the complete transmission.

the maker? of it, (kind?)
id' say its made by a top transmission maker in japan.
and fully spec'd out by Isuzu.
why do you ask?

• need parts.?
• curious.?
• what?
• does it fit other cars?, why not ask a transmission exhange shop or rebuilder. that. they can answer, that.

most transmissions of this type use a standard box but with OEM
tail shaft houses, designed by Isuzu to fit transfer case .
see here for the kits and gives you and idea of what cars it fits

http://www.importdrivetrain.com/manualtransparts.htm#ISUZU%20TRUCKS

for a diesel I have no idea, google exchanges for that.
google tranny rebuild kits.
or google swaps. for same.

i do manuals. and best is to find a donor car.
then pull the tranny and have 2 tranny
then get the kit and make one good transmission.

you never stated the problem with it?
one bad syncho? or whines or pops out of gear. or ???????????????????????????????????????
dragging clutch>?
will not shift?
stuck in 1 gear.
stuck in neutral , ?

Have a careful look at the compliance plate. It's possible the 3 looks like a 5. The 5 speed transmission may have just been put on. Sure enough GM stopped manifacturing KBD42s in 1983.

if you are trying to reassemble the cv joint ( why ever you would need to pull it apart in the first place as the new boot slips over the assembly)
do it outside of the transmission or you will damage the transmission internals
place the transmission end on a block of wood
line up the shaft and hit the top end with a heavy mallet
( sledge hammer will burr the ends )
of you are just putting the shaft back in the transmission to reassemble the front end , line up the splines and use the mallet to start the splines into place by compressing the circlip

If its a bad syncyro ring, then it could be repaired without a big parts expense, just labor
It might be cheaper to find a used tranmission and swap it out

Take the transmission out to get the exact model, because you can never tell for sure otherwise. And it is very unlikely 4 gears are actually out. More likely there is something wrong with the linkage, in or out of the transmission. But if that many gears are actually out, get a used one from salvage, because the bearings and everything will be bad as well. Used will cost less than parts alone.

Problem is the detent springs for 4/5 gear have gone weak .
If you are handy its take the top off the gearbox from inside the car and you will see the plug then the springs and balls .
If not its a transmission shop job.

could be a worn clutch\