heads ???
 

I need to replace a head. Is there an up graded head or can i just buy a used one???

If the head is bad then you could buy a used head but you would be taking a chance that it is not the best. I would just spend a little bit extra money and buy a new head IMO. Your motor and products surrounding it are not the area you want to go cheap on.

The new heads should still be checked for flatness. Some of the techs have told me new heads out of the box are already out of spec for flatness. If a head comes off my truck for any reason it's going right to the machine shop before re-installation.