Most stock arms will fit in the MVP can. There is a problem though. Once the armature is changed, the motor is no longer a stock motor. But... the chances of this getting checked in somewhere between slim and none.
Another thing to consider, is that if a stock motor has been run to the point that the comm is gone (if this is the reason you are replacing the arm) then the chances are that the bushings and possibly the magnets have seen better days. Meaning this: You might be better off buying a new motor than spending 2/3 of the cost of a new motor to purchase an arm.
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Novak Electronics: www.teamnovak.com