which is the best sound decoder for the budd railcar?.
You may need to download this particular engine sound yourself, or find someone to do it.
For example, you could get a Digitrax Sound Bug, and use a PR3 interface to load the RDC “sound project” into it. The Sound Bug is a sound-only decoder, so you would need another motor decoder along with it. The Sound Bug comes with a speaker. Even though you have to get 2 decoders, this is still probably your lowest cost option.
Other manufacturers make downloadable decoders, but I don’t know if anyone has come up with RDC sounds for them. Someone else?
What I would do it try and find out what type of engine is used in them and how many cylinders. Then look for a decoder that has that type of engine and number of cylinders. That should get you close. Since they would not have wanted to make a lot of noise, turn the sound down on the engine or exhaust sound. You should be able to find a bell and horn sound to suite you. I favor Tsunami decoders.