center console shifter knobs

I wanted to know if the knob on the center console shift lever are different design inside or have a different shift cable assemblies?
I am trying to install a center console shifter in my Barracuda and I have picked up a NOS chrome knob for it but I have to set it to where is is just barely screws into the cable assembly so the shifter will drop down far enough to allow it to shift when you push the botton on top. (I hope this make since) So I was just wondering if the knobs where different or if my cable is too short or what I needed to do?
Any suggestion of help would be great.

You may not see it but I'm using a drawer pull from Home Depot set down inside the origenal housing. The center of what your using should be threaded to screw on to the shift cable.