cheers for the low down OzEclipse.
The one on that page I am interested in is the
EQ2 R.A Economy Motor Drive - I think there may be a misunderstanding as to how I plan to use it. I would attach a gear to shaft of the motor, which would then drive another gear which would be attached to a nut which in turn drives the threaded rod (equivalent of a worm gear). This means I could have 2 gears which I could change the ratio of to gear down the speed to 1rpm.
here is an equivalent finished barn door tracker
http://www.ellenrooneydesign.com/gsp...racker%201.jpg
and a diagram trying to explain it
http://img22.imageshack.us/img22/7586/barndoor.jpg
do you not think with the combination of that and the variable speed on the drive unit that I could achieve 1 rpm? I know the thread pitch of the rod and the distance from the hinge to the rod, so if I can turn it at 1rpm it should work.