I am looking at a few Audi A4's for sale in my area but many of them do not have the ful lservice records as to when the TB or IF it even has been changed.

Any way to tell from the engine?

 

There is no good way to tell.
You have two choices: Move on to the next vehicle, if no records, or just plan on changing it as soon as you get it, and work that in to your offer price.
Buying from an individual rather than a dealer is usually the better way to go, at least you can get some decent info on what has been done to it.

 

Mine had a sticker under the hood that stated when it was changed and at what mileage. try that one first. then, if you can get them to let you. you can remove the top timing belt cover - very simple to remove maybe 5 min. and look at the tensioner - check out the TB DIY for a pick of the old and updated versions - and this method will not work on a4's that came with the updated tensioner(00,01).