Is it true that you have to replace the head bolts on a 6.5-6.2 when rebuilding or Can I use the old ones?Also can anybody tell me where I can get Pistons and rebuild kits for the 6.5-6.2 at a decent price?U.S. distributor fine but prefer canadian,EH!

You should replace them yes. They actually stretch when you torque them down, and they lose some of their strength when you stretch them twice.
That being said, I've reused them on a 6.2 and a 6.5 with no problems.

For your Parts Try Diesel Services Group (http://www.dieselservices.com/)

thanks for the reply and the parts source I will check them out.