I´ve been using TKO600 behind FE now 4 summers. NO WAY I´m going back to Top Loader.
My car is -67 Mustang and the tranny is with shortened input shaft. If I could do it ones again, I would choose "normal" lenght input shaft and use spacer in my car. This would move the shifter more closer to driver. It is now just a bit too far from my hands. Earlier engine was 467 Stroker (427) and today the engine is Shelby block based 511. The tranny has worked flawlessly. On my car driveshaft tunnel needed to lift about one inch higher than normal to gain the space for TKO. My tranny is so called "road race" version with 0.82 fifth gear(part# TCET4617). VERY nice with 3.50:1 rear end gears