So i replaced the heads on my Bronco and didn't check the casting numbers :doh0715: so now I am having a problem finding plugs. I know they are not the gt40 (did not see gt40 casting marks) series heads so I may not need those. It appears to be the larger 60-70's style plug but those are to big and the stock plugs I tried are to small (80's-90's) is to small. Is there a ford plug that works that falls in between?? I searched late last night and found someone with the same priblem and wanted to know what plug he used but now I cannot find it?