Keep Alive for 3 truck Climax

[RH]

Have a buddy who would like to put a Keep Alive type unit into his new Bachmann Climax. Seems like there would be room in the top of the coal box but would like recommendations for what brand and model to use. Also, if installed there, where would he wire it up.
Thanks for any information you can provide.
Dan

[Yard Master]

Hi Dan,

Which scale is your buddy's climax, HO, On30, or Large Scale?