Yep you are absolutely right! When I read your post it made me remember an 83 GT that a co- worker had. I built him a nice lil 5.0 engine ,installed,and tuned it for him. It did have a 7.5 locking rear axle and he had a shop install 3.73 gears in it.The car also had the crappy 4 speed transmission that acted like a 3 speed with an overdrive ( 4th felt like it should have been 5th :16suspect) He later had me to replace it with a c-4 .
That was the Dagenham four speed. Fourth was an overdrive. I managed to run a 12.40 before I killed the shift forks.