Haven't posted before, but thought this might be a worthwhile post as I hadn't found a ton of videos or photos on the upgrades from ElectricRR that really show the insides (or what sounds like what) well.
The steam engine is a 1948 Lionel 2026 with the ElectricRR Railsounds 4 (generic steam) and AC commander installed into the tender. Trucks on the tender are modified MTH trucks from a "junked" caboose for power and electrical coupler on the rear. The AC Commander, Railsounds 4 and the speaker and battery are all tucked into the 6466 tender with an 8 pin connecter to join them. The 2026 is my dads from when he was young, and it was pretty rough shape, so it has been repainted and restamped. The smoke heating element has been replaced with a liquid smoke resistor. Three additional holes were drilled into the tenders base to mount the speaker, AC commander, and the switch. Several of the factory holes were utilized with some careful planning.
The Lionel 2343 is the 1996 reissue, with a railsounds 2.5 B unit and has the AC commander installed in the A unit along with the electrical coupler. A mini commander will go into the rear A unit in the future. The original wiring was fully disconnected and left intact and all new wiring was installed, and no modifications were made to the physical train.
The video is short, and at the end are the photos of each units inside with the wiring.
http://www.youtube.com/watch?v=_MjUfaTn4U4&feature=youtu.be
Layout isn't much more than a circle and a board, as I have limited room.
I have a 2026 that I repainted that I'm also going to install the AC Commander and RailSounds in. I'm impressed you even fit the battery in, that's the one thing I leave out if space gets tight. 