Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Nice find, Paul!
I will say that I have seen more than one model 55 that appear to be pieced together with parts from various time periods. I have one myself. There may have been a period where Tom Jensen looked around and noticed a surplus of old parts and just decided to use them up instead of having them just sit there, which is something he was known for. Tom Jensen cared more about getting engines out the door than he did specifics about a certain model. I would say your engine was probably built in the very late ‘60s to early ‘70s. This is the stuff that makes collecting Jensens so fascinating.