For reference, here’s some photos of the motor that came with my D2500, along with some basic dimensions..
Sourcing a replacement motor might be difficult. Art-Tech sells replacement motor, but finding a dealer with a spare may be a problem.
Apparently the motor is used by other models. I found this 3720 motor is used on a Dynam Peaks DY8947 42" Bi-Plane sold by Nitroplanes.com, but expensive, Part # 60P-BM3720A-KV650...
Nitroplanes.com also sell an inexpensive replacement motor shaft
for this motor....