I have a 2002 4.2L a6. I keep seeing different things, some site spec pages say it's a timeing chain, others say timeing belt. Even browsing through the forums here. Witch one is it? belt or chain?

To get an answer - open the front of the engine cover(s) - fast and final answer!

haha for sure but I'm lazy.

good call though

My 2000 A8 has a belt, You can sneak a peak at it beacause the covers are not screwed in the just latched. I can pull my cover away just enough to see the belt.

Its a belt. The FSI motors have chains.

Timing chain arrived in 2005.

It`s a chain... read here
http://www.audiworld.com/model/a6/05/05A6.pdf

This thread is a couple years old & that file is for a different Audi 4.2 motor (C6 A6) than the one listed in the OP (C5 A6).