O.k., sounds goods. But (I know, I'm treading on dangerous ground here) what are things to look for to *test* the 4-matic and the N2 cells for wear?

I don't believe the car has it's records, but it appears to have been well taken care of. Of course my shop will be able to tell me more about it.

Newbie question...where would I look on the underside to check the 4-matic for leaks?

Should I just stay away?

Thanks again.