A fox tranny will swap in, if you use the fox bell, but it puts the shifter 3/4" further forward and the driveshaft ends up 3/4" shorter. Neither one is really a deal breaker, but the driveshaft spacer isn't a bad idea. I ran my cobra with the C-4 and the stock driveshaft without issue. It still had plenty of engagement on the output shaft, and it's even a bit shorter than the fox T-5's are.