I've recently bought a '66 mustang coupe, it has been 302 swapped. I was trying to verify what year 302 is in it so I pulled the starter off and found that the block casting says E7 E the third digit appears to never have been cast. I understand that the E7 means its from an 87 but now I'm curious if anyone knows why the third digit would be missing. The area where the third digit should be has the same appearance as the rest of the block so I don't think its been filed away. I also have the partial vin from the flat on top of the block it reads hf165129 if that helps. the full casting on the block is a large 21 then below that the E7 E below that ca and below that a large S. Thanks in advance for any input.