20-2621-1 Is this engine 3 volt?

Hard to say, but that was the transition period. I suspect it is 3 v, but call MTH to verify.

The instruction sheet says 3V, sound file is 3V.  Taste it:-)  G

Yes it is.

I believe most made after 03 are?

 I believe it's the first release of the SD70ACE series from them with the frame having the larger gap.

http://mthtrains.com/prod-sear...ield_roadname%3A3945

Rich Battista posted a cure by gluing on some plastic to the sides of the frame. MTH then did that mod on following models.

Engineer-Joe posted:

Yes it is.

I believe most made after 03 are?

 I believe it's the first release of the SD70ACE series from them with the frame having the larger gap.

http://mthtrains.com/prod-sear...ield_roadname%3A3945

Rich Battista posted a cure by gluing on some plastic to the sides of the frame. MTH then did that mod on following models.

 

Ya..i see what you mean by the gap.

If it has a rectangular charge port, it's 3 volt.  If round or none at all, it's 5 volt.