I remember all the problems these had when I was into Neons. They can be good, after you put some work into them.
The belleville washers that act like a spring in the center are prone to cracking on these, replace them ASAP with high quality ones. From there the axle receiving gears were not machined on the back side for axle clips so IF you put the axles in with clips...the axle was stuck...only way to free it was to break something. Also the gears were prone to having lots of burs and machine flashings. They may have since rectified these issues...but I doubt it. The neon crowd just planned on putting another $50 and couple hours of work into them to make them work. After that they were bullet proof and worked well.
Now with 5 gears!