At the seminar I heard him say that the TA belt is different because of the compressor being different and if you used a GN belt you would have problems. I did not get a chance to hear what "problems". My compressor has been changed because last summer I started getting a vibration when I turned the air on, I figured it was the compressor beginning to tie up so instead of waiting for it to go completely out I replaced it with an aftermarket. The noise went away and I was happy. Less then one year later the same exact noise is back, only when the ac is on and mostly at certain RPM's (just above idle). Hardly notice it at idle and cruising speed but as I pull away from a stop it sounds like the whole engine is shaking. Is this likely related to belt length? I don't remember if I changed the belt with the compressor last year so I figured I'd put a new belt on it but what size since I now have an aftermarket compressor? Any suggestions?