The first thing we need to identify is if you are a Bronco fan?
Cool truck, sounds like you're well on your way with it. What are your plans for it?
Once you are able to attach pics, all we'd need is two or three pics from underneath to identify it. Also there is a serial number on the bottom of the transmission that can tell us exactly what month and year it was built. It requires more work to reply back with, but assuming the transmission is mostly aluminum, the serial number will either be stamped to the bottom of the cast iron center section, or it will be stamped into the bottom of the rear flange of the front housing (between the drain plug and cast iron center section). You might need to take a wire brush to these areas the reveal the stamped numbers.