Where is the transimission dipstick on my 1999 audi 2.8 a6 quattro. how can i check my fluids ?

 

There isn't one. To check manual trans, you jack up on a level surface, remove the fill plug & insert finger. It should be at or just below the filler.

On a slush box, warm up car, jack up level surface, start car, put threw all gears, let car idle in gear (yes tires will move) remove fill plug, if no fluid comes out,
put in fluid till it does, your full.

If you are worried about the trans, you might as well change the fluid while your in there.