thank you for your question hope this helps.
FLUID RECOMMENDATIONSAll 5-speed transmissions tackMERCON (Dexron II) ATF
LEVEL CHECKManual transmission filler location
Park the truck on a level surface, turn off the engine, apply the parking brake and block the wheels.
Remove the filler plug from the side of the transmission case with a proper size wrench. The fluid level should be even with the bottom of the filler hole.
If additional fluid is necessary, add it through the filler hole using a siphon pump or squeeze bottle.
Replace the filler plug; do not over tighten.
hope this helps