Does anyone know if there is a different way to tell the difference between the 3 types of 1972 Eisenhowers besides the islands? Some of my type 1's look like they could be type 3's, maybe the islands are worn. Also, I did hear that the type 1 looks like the back of a 1971 and the type 3 looks like the back of a 1974. Anyone else hear this? Thanks!