I'm trying to figure out whether my heads are stock or not. It looks like they say "91" on the front/side of the head, and my car is a 1991...... I can't seem to find the three bars on the front that make them gt40's.
GT40 heads have the 3 bars on the front and GT40P heads have 4 bars. Also if you look at the lower head bolt by the number 1 or 8 cylinder you would see GT for GT40 heads and GTP for GT40P heads cast into the head.
E7 heads can only be positively identified by removing the head and flipping it over. It will have the letters E7TE cast into the exhaust side of the bottom of the head.
If you don't identify the heads as being either GT40 or GT40P heads then there's about a 98% chance that they're E7 heads. Some people did put non E7 heads on when working on the engine but it's not seen very much.
GT40 heads have the 3 bars on the front and GT40P heads have 4 bars. Also if you look at the lower head bolt by the number 1 or 8 cylinder you would see GT for GT40 heads and GTP for GT40P heads cast into the head.
E7 heads can only be positively identified by removing the head and flipping it over. It will have the letters E7TE cast into the exhaust side of the bottom of the head.
If you don't identify the heads as being either GT40 or GT40P heads then there's about a 98% chance that they're E7 heads. Some people did put non E7 heads on when working on the engine but it's not seen very much.
The GT would be upper case. The stock 1991 Mustang heads were E7TE heads and they were not a g and a t. From 1987 to 1996 (1995 for the Mustang) all 5.0 Mustangs and trucks got the same cylinder heads. The Cobras got GT40 heads. The 1996 to 2001 Explorers and Mountaineers got GT40P heads. Some very early 1996 Explorers may have had leftover GT40 heads from the Cobra. Lightning pickups also got the GT40 heads.
The LX and GT Mustang 5.0 got the same identical engine, transmission, suspension and rearend. The LX was slightly faster due to it's lighter weight. The notch was slightly faster than the LX due to it's lighter weight.
E7 heads can only be positively identified by removing the head and flipping it over. It will have the letters E7TE cast into the exhaust side of the bottom of the head.
Exhaust side?
I am not saying you are wrong, I have yet to worry myself over an E7 head to know for sure, but all Ford heads I have looked at have the casting number on the bottom of the intake ports. You can pull the intake and use a light and mirror to see the casting number on those. Maybe the E7 is different???