Here is a question and the corresponding answer for a ported and o-ringed Cummins 12 valve head from Piers that is listed on eBay. http://cgi.ebay.com/ebaymotors/ws/eBayI ... 344&rd=1,1
Thought everybody could use a laugh!
Q: Will this head work on my Duramax? I called around and was told it was a direct fit.
Feb-23-07
A: Well, it's not really direct. You have to cut off the intake and two cylinders. And you need to use 2 of them, so you waste 4 cylinders all together. But you can weld the 2 waste pieces together and make a spare. Since you use 2, you should be good for 900 to 1000 horsepower.