which gt40 heads do i have?

[OonDeanisS]

how can i tell which ones they are, all i know is gt40 iron.

 

[TomCat]

Check the amount of "bars" it has cast on the front of the head. 3 for GT40s, 4 for GT40Ps.

 

[bubba-dough]

The GT40P's say GTP on them also

 

[TheBocSez]

Something else to consider if they end up being GT40's and not the GT40P is to check the hole size for the head bolts. If they are 7/16 they came from a Cobra most likely and will have the smaller combustion chamber. If they are 1/2 they most likely came from a lightning and will have the larger chambers which will lower you compression.