How to thread on TKO600, need advice.

I went with a 3.74 rear.............With the the TKO I can be at 70 with a 3000 RPM spin which will be a hellva lot better than the 727 .

WTF?? My Dart before I took it apart is a Ford whatever is close to 3.7X, and with the tires I run, a 1:1 (727 + converter slip) is somewhere around 3300? I'd have to go look in the garage to see what size tires.....it's not jacked up or tubbed or anything