Being new to dcc I need a little help. I have a ho P2K GP30 and would like to add sound, I’m not sure which soundtraxx sound decoder to choose.
According to Soundtraxx’s pages:
http://www.soundtraxx.com/products/dcc/ll110.htm ( 820070 EMD 1st generation (GP7/9, GP30), low-cost, drop-in)
http://www.soundtraxx.com/products/dcc/dsd090.htm (probably 821200 DSD-090LC for EMD 1st Generation, also low-cost, but needs more wiring, and some people aren’t so impressed with the sound)
Any of the following DSX:
http://www.soundtraxx.com/products/dcc/dsxsound.htm
825201 EMD 1st Generation with WABCO Airhorn
825202 EMD 1st Generation with Leslie S3 3-chime Airhorn
825203 EMD 1st Generation with Nathan 3-chime Airhorn
825204 EMD 1st Generation with WABCO E2 single chime Airhorn
825205 EMD 1st Generation with Nathan M5 5-chime Airhorn
825208 EMD 1st Generation with Nathan P3 3-chime Airhorn
(best sound of pre-Tsunami, but require a separate motor decoder)
I’ve put DSX in several locos, and it’s not all that difficult… IF you can find space. 
Brian Pickering