disconnect driveshaft from front diff, and rear diff where it connects to the transfer case, remove bell housing bolts, disconnect clutch hose, place a jack under the belly pan and remove the belly pan ( skid plate ) bolts, move the whole mess back a bit to clear the input shaft and lower the jack to the ground.
unbolt it =]
Most likely the ax15 manual transmission
Yo have to remove the transmission.
You have to remove the pan if there is no drain plug
The ax5, AX15 transmissions in a 1990 Wrangler use 80W90 gear oil.
You may have to remove the shifter and realign forks in the top of transmission--problem usually caused by wear
How do you change the steering shaft in a 1990 Jeep Wrangler?
how do you remove the doors from a 2004 jeep wrangler
Half way up the side on the drivers side of the transmission
The amount of oil needed for a 1990 Jeep Wrangler is 6 quarts. The Jeep Wrangler uses 10W 30 oil.
To edit original question....Jeep Wrangler 2005 manual transmission
you have to remove the panle on the outside of the jeep between the hood and the windshield. 4 screws.