Actually, any motor from that era will work.
Kato used a motor called the GM-5 motor. It was the same motor in:
Kato GP38-2, GP50
Atlas RS-3, RSD12, GP7/9 etc.
You could easily get a motor from any of those locos- the only difference is the little motor tabs- which you already have on your motor.
You real problem may be more than you are expecting.
The GP38-2 mechanism was amazing in its day..... when new.
But any time the flywheels were pulled off or any tinkering with the motor.... it was almost impossible to get them to run silently again.
The reason is the flywheel/worm dumbbells are connected to the motor by a Delryn joiner (tube). Because it's plastic, it bends. So it is a real challenge to get everything absolutely perfectly in line. If not perfectly straight, then wobble is introduced. That's why Kato changed the design with the GP50 and uncoupled the direct connection between the motor and the dumbbells and used a U-joint instead.
If you can find a replacement GP38-2.... your best bet is to try to carefully lift out the whole drive train in tact and install it in yours.
I used to own lots of these and loved them for a while. But when they got noisy compared to other locos I replaced them... except for one.
