I have never seen a 3 leg with what I thought were original "universal" steps so that would put them pre 1958. They are in my 1952 catalog tho. I have run across more of the trussed tripod 3 legs than the easy to build up ones but 3 legs just were never popular in the WestInteresting for sure! When did aermotor quit offering the three legged tower? Or do they still?
Ron Stuaffer
Montrose CO