FT is likelt perhaps Truck, can officially answer, and have the Ford Edsel thing kicked back and forth all the time... The FT motors were found in the medium duty trucks, and for whatever the reason, were about 1 cube off the FE equivalent. 361 and 391 were common FT motors. You could find them in straight trucks and the like. The FT motors actually were still used as far as 82, had to work on a cabover truck that looked more like a late 60's early 70's truck that had an actual title of 82...