I was out surfing and found this Interchange Guide for Craftsman to Tecumseh model #'s. Thought you folks would like it here to find it easily. Here's a list of who made what (shorter that TD&H's above), but I think it pretains more to the tractors.
Here's the engine model interchange. It starts with vertical shaft engines, the horizontal's are further down. If you have a Craftsman tractor with a Tecumseh, but a Craftsman model # on the engine, this will tell you which Tecumseh it is.
craft_tec.pdf 9.12MB 42 downloads