Hello there forum. I bought what I was told is a 1980 Larson 18ft tri-hull. However, I think it's quite a bit older than that. There isn't any hull number on it on the outside of the transom. I found a tag on the inside of the transom with a 6 digit id number on it. It has a 120hp i/o in it, and the engine numbers date it to between 1975 and 1978. As soon as I reach the magic number of posts, I'll post some pics. However, if you all have any info on how to find out what I actually bought, please let me know.