[engineguy]

In the recent past, cylinder heads used in NHRA Super Stock Modified class had to have an OE casting number. However current rules state that aftermarket aluminum heads may be used in this class. But it also states that the heads must be on the "NHRA approved head" list. Make sure that the heads you chose to use are in this NHRA "list" and keep a hard copy of this list in your files. Yes, it is true, NHRA has been known to change their minds on this sort of things in the past. If your heads happen to get dropped from the list in the future, you should be "grandfathered in" with the list of the approved heads in your possession.