I have put the same motor focus on my 6" f8 frac and it's a long way ahead of using the fine focus knob on the GSO linear bearing focuser, but I had to glue the gear wheel to the knob... it just spun around otherwise. The other choice was to drill a hole into the knob and put in a self tapping screw to hold the gear wheel in place. I get zero focusing wobble now
Very happy with it.
Matt