You might find more info here:
https://ogrforum.ogaugerr.com/forum/o-scale-narrow-gauge-forum
Take a look here:
http://www.pacificcoastairlinerr.com/mogul_tsunami/page2.html
There are two DC Moguls featured on this site and this page is just one - different decoders. So, follow the links in yellow at the bottom of each page and you'll find them both and their tenders eventually. Takes a while. I am currently working on one of these DC Moguls. It was all red. I took it all apart and painted - all black now! Wire routing will be the biggest problem whether you put your decoder in the loco or in tender. I am putting a WifiTrax control module in tender controlled by my Amazon Fire. Headlight is now LED. Tender now has electrical pickup on trucks, backup LED, and oil bunker(no coal). I'm all done except for final locomotive reassembly but I'm still working on the wire routing out of the boiler. Bachmann did not design this early version of the Mogul with DCC in mind. In short, it can be done and it's worth it. Good Luck with On30 adventure.
This post probably got stuck in moderation, which should be over for you in another couple posts. I'll give it a bump.
There is not a lot of On3 discussions here, but maybe someone knows.
Henry
COB Potomac & Northern
Shenandoah Valley
I recently purchased a Bachmann #25227 On30 Christmas Mogul. I’ve installed decoders in a couple of these before, so I thought the procedure would be straightforward. However, this has some extra underframe details that appear to make it more difficult to remove the locomotive shell. I'm having trouble accessing the tabs below the cab and the smokebox that secure the shell to the chassis. Has anyone tried to install a deocdewr in one fo these? Any idea? I'm grateful for any response. Thanks, and Happy Thanksgiving.