Thanks for your help.  That site was perfect.

I have a Bachmann Spectrum Maryland & Pennsylvania 4-4-0 #4 which is DCC equipped. I also have a Bachmann Spectrum Maryland & Pennsylvania 4-4-0 #6 which is DCC and sound equipped.  I love the sound on the #6 and would like to add sound to the #4.  I have looked inside the tenders of both engines (which on the outside appear to be identical except for the numbers) and saw what appears to be a plug-n-play sound module and speaker in the #6.  My question is simple, does Bachmann sell the plug-n-play sound unit and speaker (light steam) separately?  If so, what are the part numbers and how do I order?  If not, can anyone recommend where I could obtain a plug-n-play sound unit and speaker?

This ten wheeler is the 53" driver model.  I will probably go inside of the tender this weekend to see if all I have to do is puul the plug and pop in the DCC decoder.  Thanx to everyone for your help.

Thank you.  If I understand you correctly, I can also put sound into this ter wheeler.

I have a Maryland & Pennsylvania 4-6-0 #27 made by Bachmann that did not come DCC equipped like my Maryland & Pennsylvania 4-4-0's #'s 4,5 and 6 that were also made by Bachmann.  Can I convert the 4-6-0 to DCC, and if so, how do I do it?  I am not the world's brightest bulb, so I hope the conversion will be easy.