Since no one else answered I'll give you a bit of info.

Short version: The spurs from any of cen's 1/10 scale MTs buggies and rally cars will work.

Long version: All of CEN's 1/10 scale nitros (except touring cars) are based off of the same basic design. They MT buggy and rally just use different A arms, shocks and shock towers. The old series was called the "funfactor" series, and the new Magnum and talon have some differences.

Compared to the old Funfactor series (MT2, Buggy-2, ST, ST2, Rally), the newer Magnum, MT-spec 3.0 and Talon have a longer chassis, longer rear driveshaft, different fuel tank, different "top plate", slightly different "counter gear support", .18 engine instead of a .16, and a different steering servo mount. Besides those parts, all of the suspension, diffs, bodies, engines, electronics, wheels, gears etc, are interchangeable.

You can get the part numbers for the gears from this exploded view. http://www.cenracing.com/downloads/nx_ev.jpg