Bachmann gp9 add sound

[Train res]

hi everyone
I am brand new at this message thing
I have a #62810 Bachmann GP9 Diesel DCC CN #1725( one year old). I want to add sound
I have it disassembled with no problem.  I would like to know what Motion /Sound all in one
decoder I should install and the speaker as well
This locomotive has an 8 pin dcc decoder already present.
thanks for your help and advice

[Trainman203]

https://soundtraxx.com/

[rich1998]

Look in the HO Bachmann decoder selector page for that one you need with suggested speaker and I think baffle.

Rich