First, I have a stripped hole where the exhaust stud threads into the head. It's a stock 75 2.0 . The PET manual shows #014 397 9, which is AM8 x 56 (what's the "AM" stand for?) qty "8"ea. It also lists #014 684 1, which is CM9 AX MB x 56 (what do "CM", "AX" and "MB" stand for?) qty "X"ea. ( X ???? ) Are there possibly two different diameter studs that were used on the 2.0? The AM 8 is 8mm, right? If so, is the CM9 a 9mm?
Secondly, is there any reason I should not drill and tap/heli coil the head in place from beneath the car. It's looks do-able as hell but thought I would ask here, first. Thx

I would certainly install a 9/8 mm stud first before tapping any more oversize. The 9mm (still 8 on the bottom) is a stud installed on the 1.8 models. If everything else fails you can install as large as a 10/8x56 stud.

The current studs do step down in size. One end is 8mm x 1.25 and the other end must be 9mm because it's too loose in a 10mm die. However, I do have 2.0 heads so maybe they were changed out before?? Anyway, the old hole is pretty smooth and there are only 2-3 threads remaining. Anyone here sell the 10 x 8 56 stud that George mentioned or is it dealer item. Also, what is the correct number/letter drill bit for a 10mm tap?

AA has the 10mm to 8mm stud in their catalog. I have seen them. He has 8X8 - 9X8 and 10X8. Download the pdf from their site to see them and call.

Check with AA on Monday before buying the right tap and heli coil.

John

http://www.mcmaster.com/#step-studs/=83t12j

And you can get taps, drills, whatever else you need. I always get stuff in 24 hours from them.