Hey Mike,
Your serial # indicates early 1954. If your frame has the mounting pads, then that frame is from a super. It is possible that someone repaired your tractor at some time using whatever parts were available. You should get in touch with Ollie Schaefer, he is better versed on Fleetlines than I am. Ollie could tell you if that is a 77 with super parts, or a super with 77 parts.
Later, Andy