K4 Pacific 4-6-2 DCC Cab #5448 with Tender K100916

[trainman1000]

 What is the best way to add sound to a this locomotive?

[Tenwheeler01]

Depending on which tender (with or without a speaker mount.)  Just look at the bottom of the tender for sound holes.  I now only install Tsunami 2s or WOWs in steam locomotives.  They are both around the save price and have the best set of features for the money.
I usually go with the TSU-2200 or WOW10, With a 9-Pin JST to NMRA 8-Pin Wiring Harness, 28mm round speaker (1 1 Watt (Nominal) 2 Watts (Peak).
  If you have the tender with speaker mount. I use the SoundTraxx gasket to get a good seal in the mount. And a couple of dots of hot glue just to be sure.  Then I solder the speaker wires to the speaker.  Then just plug harness into the 8 pin socket on the light board and decoder and then plug the speaker wire plug into the decoder (if you unplugged it).
  With the older tender you will have to drill holes in the coal load for sound to escape and hot glue the speaker to bottom of the coal load. The rest of the install is the same. 
  The TSC web site has instructions on how to install there complete WOW kit for both tenders.  They also have great example of installations to look at.  Also SoundTraxx has vast collection of how to videos.

I think all my Bachmanns have sound decoder installed in them.  And most of them are DCC ready locos.
Also I try to use the factor circuit board when possible. The circuit board has the correct resister to match the factor lights. And for the models where the wire plugs are on the loco, Altering the wire length can cause unwanted issues. 

This may be too much info. 
 

[trainman203]

If you are a beginner, the best way is to pay somebody to do that work. I have an individual do my work and the cost is around $100 labor. You might say that sounds like a lot, but, factor in all the errors you're going to make if this is your first time, that you might fry the decoder hooking it up wrong, and you may poke a hole in your tender shell with the soldering iron like I did.

The labor cost will avoid all of that, and get you something that works right the first time.