Finally, a solution to the 5 foot Promatic shifter cable.

I've gone through the same thing. Not sure what you're working on but on my 68 Dart 727 the 3 foot is too short. Bends too tight and the cable binds. I use the 4 foot and it fits way better than the 5 foot but there is still a spot that gets close to my header but a length of fuel line slipped onto the cable seems to be plenty of protection. Another issue I had is that the eyelet on the shifter side of the b&m cable is bigger than the on on the Hurst cable. When you push or pull to shift the first bit of movement is just taking up the slack in the eyelet, and not moving the cable, so it wouldn't fully get into gear sometimes (Not sure if that makes sense) After many hours of hair pulling attempts to adjust the cable I figured it out.. I ended up making a bushing that took the slop out of the eyelet and problem solved. Not sure if you will have the same problem, but just a heads up. I also might still have the 3 foot cable around if you want to give it a go, cover the shipping and I'll send it out.