You probably have a SROD (single rail overdrive). Common on very early 80's Mustangs and Crapi's. Basically it's just a 3 speed transmission with 4th being OD. Nothing to write home about (not the strongest in the world) but as mentioned, they do have a very low rotating mass which the circle track guys like.

Yes theoretically it is a top loader, but it is not what we call a toploader. What we refer to as a toploader is TOTALLY different...levers on the side like an old 3 speed truck transmission.

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record breaking '75 Maverick bracket car 2 time track champion, '84 Mustang LX bracket car, '78 Fairmont Futura, '86 Merkur XR4Ti, '95 F250 PSD, 00 F150, '03 SVT Lightning (DSG) #888