Are you asking about the Centuri model or some other rocket?
I have a lot of information about the Centuri Long Tom but I'm not aware of any scale model or full scale rocket called the Long Tom. That doesn't mean there isn't one. It just means I haven't heard of one.
Assuming you're talking about the Centuri model, here's what I know. It was introduced in the 1971 Centuri catalog. There is nothing about it being a scale or sport scale model. It has always been a two stage model but I can't see how it ever had a 3 engine cluster in the first stage.
First of all, the catalog description doesn't say anything about it. Secondly, the body tube diameter of the first stage is 1.34" which means you couldn't get three 18mm motor tubes in it (or even two). You can get three 13mm motor tubes in that size tube but there were no 13mm motors available from Centuri in 1971. Subsequent catalogs from Centuri (1972 - 1981) make no mention of the first stage having a cluster. So, I'm not sure what you're refering to.
I'd be interested in finding out more about this Long Tom.
Thanks.
Romie Lucas
NAR 54477