Based on my experience,

I would use the Soundtraxx unit, it's worth the extra few dollars for many reasons. Never had a bad Soundtraxx, but a few bad MRC's....
Make sure you use the biggest speaker you can fit in there.

If you are uneasy about the install, find a good installer and have them do it for you.

Here is a link that may be helpful to you with the wiring:

http://www.tcsdcc.com/public_html/Customer_Content/Installation_Pictures/HO_Scale/Rivarossi/0-8-0/0-8-0.htm

and here is a link to various prime mover sound decoders and whistles. Scroll down to the light steam decoders.

http://www.tonystrains.com/products/soundtraxx_tsunami.htm

Thanks for the links but my engine has the motor in the engine cab, it's a really old model. Installation should be close though. Looks like the Tsunami is out. Besides being expensive, the link above to tonystrains states it requires the Power Pax Programming booster to program on the program track. Plus you have to buy the speaker separate.  The link for the Power Pax takes you no place, but I imagine that the whole deal will be near $200 before I am done - just for one engine. Too expensive for my blood.

Just did some more research and reading. I guess for any sound decoder I will need either the PTB-100 or the Power-Pax to program decoders. This DCC is not a poor man's hobby.

Alex,

Before dumping the thoughts of Sound there are some alternatives depending upon which DCC setup you have. Although some command station / boosters do have problems with sound decoders on programming tracks, they will often be able to program the decoders in Ops mode on your main track. Some units like the updated Digitrax Zephyr seem to do fine on the programming track without a booster.

What are DCC system do you have? Do you have JMRI?

I have both a Tsunami and a Zephyr (the original, not the updated version).  At first, I was unable to program the decoder's address, but I found a way around it.  There's a setting (I'm not at home to look up which one at the moment, but it's buried somewhere in the manual) which lets the Zephyr use the entire main line as a programming track at full power.  Obviously, you have to remove everything else from the main first.  Once the address is programmed, everything else can be done in ops mode.  Using that technique, I had no problem setting up my Tsunami.  I do not know, but I assume other DCC systems have a similar capability?

Some way, some how, I am going to have sound in this engine. This engine is rare enough and pristine enough to make it worth it. I see junkers on eBay going for $30+, and running condition ones for $150. The price sticker on the box I have is $37.95, don't have a clue when I bought it, in fact I didn't know I had it. wonder what else I have packed away.

Guess I'll have to sweet talk SHMBO and see if I can get an advance on my allowance for the next 6 months and get the job done.

I'm sure you'll enjoy the sound.  I've heard good and bad about all decoders, which is the usual way about anything.  My personal preference is for QSI, and Soundtraxx is a second choice, mainly because of quality, and also features.  If this is an 0-8-0, and not an 0-8-0-T, then you could put all the electronics inside the tender.  I'm in the process of rewiring one of my steamers in that way.

Enjoy!

I would check how much current the motor takes, the Loksound Select, my preference only supplies 0.75 amps, you maybe better off with an Aux 6, 73417, slightly more expensive but can take 1 amp and has a wire harness probably easier to wire in your loco than the Direct. You may find an old Aux 4 (four outputs) cheaper. If you know someone with a Lokprogrammer the sounds can be updated if a better sound project is released. 

The Loksound will probably give better, definitely easier to setup, motor control.

Programming depends on your system, my up to date Lenz can program Tsunamis or Loksound with no problems, before upgrading Tsunamis were trouble.

Mike Ruby