I noticed that Walthers had made some revisions to the Alco RS-2 after they bought Life-Like. Here is a brief comparison between the Life-Like RS-2 and the Walthers RS-2:
Life-Like RS-2: Athearn-style trucks, open frame motor like Atlas Alco switchers, and an Atlas (China) style light board. If I were to install a decoder in one of these locos a Digitrax DH163AO would likely be the best fit.
Walthers RS-2: Completely redesigned trucks, flat can type motor, and an all-new light board with a 9 pin DCC plug. A Digitrax DH123 plug ‘n’ play decoder fits perfectly.
I have a pair of the Walthers units and they run quite well.