casting #`s

These pics are of my rebuild and my drivers casting #s. The top one was the original 225 engine from a 69 dart 3 on the tree. I had never seen the AM on a slant before this one. The bottom is the original 198 slant thats in my 71 Scamp with a column automatic. Thats BF but they both have the same casting #s. They do both have forged internals though. I dont really know what the letters mean but I know they are different.