On-line GM part numbers available?

[hiredmanDan]

If there is a link to an on-line GM part numbers list for the Duramax 6600 engine, would someone please provide that website link to me? Thanks in advance.
I had a belt pulley fail on my 2002 and I need the part number for the pulley which is the small pulley closest to the adjustment pulley. I have only one alternator and there is a pulley just before the alternator and another one just after it. The pulley bearings must have failed and the pulley came apart and took out the belt. The adjustment pulley is fine and I just need to replace the one pulley that is in between the adjustment pulley and the alternator. I think it has to be a smaller pulley than the other one that is right next to it. The dealer sold me the same pulley as is on the other side if the alternator but I am sure it is too big. I'd have to stretch that new GM belt over an inch if I use the pulley he sold me.
Any links, suggestions, or other help would be greatly appreciated. And by the way, does anybody have a GM parts source that is considerably cheaper than the dealer? That new GM brand belt cost me $62 yesterday!

[DmaxMaverick]

$37 for the belt at www.gmpartsdirect.com (List is $62.04). Their prices are usually about 1/2 of the dealer list, for the same GM part. If you need to get other GM parts, it's a good idea to get them at the same time. They can get a little ridiculous with their S/H charges on small/single item orders. Still way better than a local dealer charging list prices

The pulley may have been updated. Larger is better, if it fits. A larger pulley is less stressful on the belt, and it will turn slower at the same belt speed.