The 45 tonner already has a spot inside the air tanks underneath with speaker baffle built-in on the frame.  A Micro Tsunami will readily fit in the cab, but with little ingenuity, it will fit where the decoder portion of the pcb in the loco is made to be removed.  Soundtraxx has the new GE Cummins Diesel Micro Tsunami which would be a decent facsimile of the real thing even if it isn't really twin CAT diesels.

To help everyone find the decoder programming instructions buried in the E-Z Command menu item at the left, why not place a link to them under the Frequently Asked Questions, DCC board?  It sure would be easier for someone to find just jumping into this message board.

One thing that was missed in all the discussion was recommendation about the tools to do the job. The following link will get you to my suggestions about what to have to take on such projects: http://www.frisco.org/vb/showthread.php?t=2849 

I recognize that I am sending you off-site, but the frisco.org forum is free to all and I am the Electronics moderator there.  My suggestions come from nearly 40 years of electronics hobby.

My favorite silent decoder is the TCS M1.  Excellent lighting configuration control, Back EMF for much smoother creep and slow speeds, very small (thing little finger fingernail) and best of all - their goof-proof warranty.

For sound, none can beat the Tsunami.

Add a few drops of dishwashing detergent to the glue/water mixture. This will break the surface tension of the water and allow it to soak into the ballast.  You may have to experiment with the quantity of soap.

Why provide parts lists that identify each part if they are not available? Example: I wanted to purchase 8 of the oil tank hatch 00W01 for the Spectrum 4-6-0 tender as well as a list of other parts, but they as well as most individually listed parts for other locos are not available.

Is there somewhere that we can get access to locomotive model number to description cross reference?  It would be usefull in searching for models that you have discontinued but may be what we are looking for.