Aristo/Crest Revolution (Trackside/High-Current) Sierra Sound combination with Sierra interface board. Sound chip in the Sierra is currently EBT #14, but can swap it out for C-16 or K-36 chip instead.
I used this combination in my Bachmann K-27 until I converted it to Airwire.
The Aristo trackside unit is the 1st generation (non-sound) version that has outputs for directional headlights. (The later sound version does not.)
Price - $200
Later,
K