To the best of my knowledge, there are no build cards for the Fleetline tractors, and older. Just Supers and on up. But I can tell you that the C 77 D is the transmission code for your tractor.

At that time, C 77 was code for a 77 transmission, and the D told which one you had. 

C 77 D was the regular speed row crop transmission with 11/50 bevels.

C 77 C was the special low speed row crop transmission with 9/48 bevels.

C 77 F was the multiple reverse (4 forward and 4 reverse) row crop with 11/50 bevels.

C 77 E was the regular speed transmission for a Standard 77 with 13/48 bevels.

There may have been more, but these are the ones I have right now.