@ chevy72blue
I know we got into a brow beating contest before, and I would like to apologise. Here is a link that can better explain the vortec head which is the L31 head.
One thing that I would like to clarify the "vortec" that has been rated so well is the L31 design that first apeared in the 98 trucks. But GM calls just about all their motors after 97 "vortecs" 4,5, 6,and 8 cyls use the Vortec name. Thats why you see a lot of people selling vortec heads..... but it is not the L31 vortec head thats been a good performer. Someone may be selling you a "vortec" head with out any intended malice, its our own fault we made that Vortec name stick, when it can mean alot of diffrent models.
http://www.sallee-chevrolet.com/Cyli...ds/Vortec.html