Hi Mike
I have orderd the same focuser for my 12" GSO (whish this one was on here a week ago) You will need to space it,It will cost you about an extra $40.00 to do so but well worth it.
Here is a link so you get the idea, and go on buy it you know you want it
And im not trying to sell this they are a very good peice of gear.
http://www.focuser.com/cgi-bin/dstor...pgrade+Adapter