[captain harlock]

There are three sizes of these brushless motors:
S= short can and rotor= standard size motor. No good for big trucks.
L= long can and rotor= 10mm longer than the S size= more torque and run time= good for stock e-maxx
XL= Xtra long can and rotor= 10mm longer than the L size= tons of torque and a very good amount of run time, too.

The 9920 should work with most of them, but not all of them.

As Boss302 said, the Wanderers have better bearings than the Feigaos.