Before all the purist jump me for this question i have several of these loco's for my 6 year old son. if they get trashed it's no big loss like daddy's MTH or Proto H2K stuff or anything else I spent way too much money on but shhhhhhhhh don't tell the wife. These things growl like an old coffee grinder. I know several companies make replacement decoders but if I'm gonna change em why not add sound.
Has anyone installed a sound decoder in one of these and if so what did you use?
http://www.bachmanntrains.com/home-usa/products.php?act=viewProd&productId=1505
Probably the best alternative would be the Soundtraxx LC ("Low Cost") DSD-101LC for EMD 2nd Generation engines. I haven't done this particular engine, but I'd probably try to use a lightboard replacement decoder - then you only have to find room for a speaker. A 1/2" round one with enclosure will fit pretty much anywhere, a 1/2" by 1" oval one will often fit too.
http://www.soundtraxx.com/dsd/lc/index.php?p=dsd101lc.php
If you're OK with the way the supplied Bachmann decoder works, you could also add an MRC "Sounder" diesel sound unit...but most folks prefer to replace the cheapo Bachmann decoder. However the Sounder by itself will be about $20-25 cheaper than the sound-and-motor LC decoder...but you have to find room to add it inside the engine.
http://www.modelrectifier.com/search/advanced-search-results.asp
Thanks for the reply but I think I have purchased my last MRC decoder. I have just been having way too many issues with the ones I have while also running 3 digitrak DH123P's and a couple of soundtrax without a single issue I have lost interest in MRC. The decoder in the engine is junk at best it makes so much noise it almost sounds like gears grinding. So it's going in the round file.