I need a diagram for putting back together a craftman mower deck and belts.

If you use Google... you can find the entire service manual in PDF format. That's how I found the one for mine.

Also... I'm not sure every year model and size craftsman tractor use the same belt layout.

Hi,
I you have the model number and provide to this link, it may well have the breakdown:
Owners Manuals & Product Manuals | ManageMyLife (http://www.managemylife.com/mmh/owner_manuals)
Peace,
Clarke