T5 Five speed slant six 74 Dart Sport.

I believe that's what mine is as well. With the 3.55 gear and the 26.85" tall tire, it makes for great performance and great highway driving. I'm now just over a week into driving this to work and one four hour round trip, and it is all around fantastic. Being I need to replace my SureGrip anyway, I may put in a 3.73 and see what that does for me; would be just under 2400rpm to do 75mph.
I just got done putting a 4.11 gear in the Ford 9" I plan to put under Vixen when I make the transmission swap. Even with the 4.11 final ratio will be only 2.79.