Goody, is the 6 speed physically larger than the 5 speed??

Yessir. Requires the torsion bar crossmember hump to be completely reconfigured. Quite a bit more work vs a 5 spd, but if one were to go to coilovers, it wouldn't be as bad.

I have the Tremec 5 speed in my Cuda and the 6 speed in my SRT 10. I love the 5 speed but I'd rather have an auto in my SRT 10. At wide open throttle you can't shift the six speed at all. Locks up in gear, really sux. Centerforce clutch aluminum flywheels in both. Only real difference besides counting gears is the SRT has hydraulic clutch, whereas the cuda is stock hard linkage.

SORRY FOR THE HIJACK



this is a common problem with 6 speed trans,a N2MB WOT box would probably cure your problem.

info link
N2MB WOT box

Out of the transmissions mentioned I would much prefer the Passon A-855 5 speed. Absolutely no modifications needed. The only other 5 speed transmission that I know of that is not supposed to not require modification is the McLeod "Muscle Car 5 Speed." They say the GM version is out now with the Mopar version coming next year.

https://www.mcleodracing.com/index.php/driveline/muscle-car-5-transmission.html