Smells like Gear Oil

[fixkick]

Hello
Have a 96 tracker 5 speed 2WD. The transmission was rebuilt 5 years ago. Last year I changed the clutch and put in some amsoil manual trans fluid gl4. 
I noticed lately when I’ve been driving for a while with windows up that I smell the tranny fluid. While driving I pushed up the rubber gear shift cover and saw a little smoke and it smelled worse. Could the fluid be pushing up into the shifter box?
Can the fluid be over filled or under filled and give this symptom?
To be on the safe side I ordered two quarts of the oem GM tranny fluid which should arrive later this week. 
Any advise would be appreciated

the right side of the box has  fill hole, and is the level hole, fill only to bottom edge of side fill port. (10m  inside square drive)
the top of the box  has 2 rubber rail plugs that can fall out or leak. they are RTV glued in best.
there is no GL4 in the shifter box this is greased only .  the shift rails would need to be a wreck to let GL4 to the upper shift gate box. blow the gate box yes. o
the top vents on the box must be free flowing (air  vents) and do not block the 4wd breather to trans behind engine head must not be plugged up ,there a water baffle on top of that hose
and some find it vent baffle missing so cork it, this is a dead wrong act blocking any air vents. to 2 axles or to 5sp top of box. air vents.

if not overfilled I be the vent is blocked, it must breath air.

some nuts try to fill the box via the shift gate and fails, none hits tbox below, and it burns up drained.
this  is the shift gate that is grease only.



all this is grease only no GL4 lube

part 20 is vent baffle must never cork like plug it is a vent.
GL4 lands only on parts ID 1 and 2 forks. and 3, 4, and 5 rails and ends there, plugs  13  both not missing and wants to leak, lacking RTV sealant.


good luck finding true cause, cheers and good day to   you.