Butch,
Welcome to the site as a supporting vendor. Your product looks like a top quality piece that is designed very well. I just wanted to inquire about the late 07 and up designs. From your site the instructions are as follows for installation.
Installation is easy! Just unscrew the stock shifter handle with a few deft turns to the left, Add a few drops of thread-locker (included) and screw the new handle on. Voila’
On the 07 and up shifters the shift knob is not threaded, it is a pressed on knob with the lower cap snap locking it in place. I have been considering changing the shift knob on our Challenger as well and your shift knobs look like a good choice. Do you have these in the newer design?