A friend has a TKO600 in his stock-appearing '71 Charger R/T, and he absolutely
loves it.
That being said, they don't like hard, high-RPM dragstrip launches with good traction. Lots of tales around the internets of guys breaking Tremecs in their high-horsepower street cars at the strip, usually with slicks installed. As far as modern transmissions go, though, they're really the only game in town.
I built a wide-ratio A833OD for my Challenger, using a non-OD iron case and fixed countershaft for maximum strength. It's certainly no 18-spline, but I don't expect any issues with occasional abuse behind 340 Six Pack with street tires, either. It'll probably only go to the strip once, run straight off the 125-mile drive to the nearest quarter (no tire change, uncorked exhaust, etc.).
My "strip" beater runs an early A-body gearset, which is the same as a B-body close-ratio except first gear is a 3.09:1 ratio instead of 2.66:1. With 4.10s out back, it's the equivalent of a 4.76 ratio in first with the 2.66 first (~5.13s with the later 2.45 first, or a 727). On 25"-tall drag radials, first gear is done
quickly.
It still sings at highway speeds, but that's not a concern with that car.
