I posted this on another site so I thought I'd try here. I went through a ton of posts concerning engine numbers and could not find these numbers at any site. I got these from a local engine rebuilder who says that this is a full pressure 235 that he has on his shelf and is willing to sell. He also could not find these numbers in his books. What is it: engine # 505101. He said it also had H207 and 3210. Thanks for any help. Brian