Check/fill plug on MKIII manual trans

I know this sounds sad I can't find it, but I need help finding the check/fill plug for fluid on a '94 jetta 2.0 with manual tranny. I have the Hayne's manual and it says it should be on the differential casing and look like a hex bolt or something similar, close to the tranny ID number. I see the ID number, but no plug. The only hole to the tranny I've found is on the top of the bell-housing, and it's a plastic plug(what is this by the way?). Thanks to anyone that could help.

the check/fill plug is on the right hand side of the motor, at the rear of the tranny, you will have to remove the plastic splashguard (it just pulls off), i believe that the socket it a 17mm hex, its not a bolt. its a hex plug.

sorry i meant left hand side, the drivers side

damn... I've been searching for that like forever too. Hahaha

mmichalak i checked where you said and i think i know what you're talking about, but it's at the end of the transmission, not on the differential casing like the hayne's book says, the only hex plug i can find theere in on the very bottom facing the ground, so i figure it isn't for fluids. It's seriously pathetic i can't find it but transmission fluid is crucial so i'll keep trying. Write back if you have any more advice. Thanks.