what is needed to add sound to a #80101 and #83407 Bachman loco? To add DCC and sound to analog mantua 2-6-0 mogul?
For the Bachmann engines you listed, any sound decoder will do (usually people will go with a Soundtraxx TSU-1000 light steam decoder since it is only a 4-4-0 but you could also use a TCS WOW sound Steam decoder or even a Digitrax or ESU sound decoder as long as you have the decoder programmer that matches the brand of decoder. In other words, the Digitrax programmer with the digitrax decoder, and the ESU programmer with the ESU decoder) as long as you have the NMRA 8-Pin to 9-Pin JST wiring harness for the decoder otherwise you could solder the bare wire ends directly to the decoder socket on the PCB in the tender. As for the Mantua 2-6-0, I can't give any advice there as I do not own one of those nor have I ever fitted one with a sound decoder because of the fact I don't have one.
I can only recommend Soundtraxx. Look at the below link. Store it in Favorites for future use.
http://www.soundtraxx.com/choose/step3.php?t=ho&s=Bachmann
I have done the 4-4-0 and 4-6-0. The 4-6-0 with small drivers has a small tender like the 4-4-0. I used the 750 in both. I removed the PC board and did a hard wire. 28mm speaker.
Search HO forum for 4-4-0 richg.
Litchfield Station is a very good on line DCC supplier.
Below is a link on how to hook up a TSU1000 to plug in to the 8 pin socket. Click on Curriculum, SoundTraxx Tsunami.
No idea of room in the 2-6-0 tender. I normally measure twice and cut once.
http://www.mrdccu.com/
Rich