$700 is stupid cheap for that drive, however, someone has broken the living crap out of the upper spanner nut and will have a hell of a time getting it apart...

This drive has (or should) a 1.50:1 ratio, good stuff...
edit; by the way, I have a new spanner nut here at the house and if you could get it apart may increase the overall value of the drive unit...
Do you have the rest of the system?
Lemmeknow

GT