The dog leg headers will fit on the rectangle heads with no problem, just use a good quality gasket. Rectangle headers won't work on dog leg heads, though. That little dog leg will be open, ya know. But the rectangle ports fit inside the dog leg, and will seal fine. What ever header you choose, check the flange area for flatness....Russ __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com