I have a pair of Athearn HO scale locos which I purchased used. I think they are GE U-25 or 30? They did not come in the original boxes. 
Both locos came with mrc motor control decoders that were plugged direct into the top of the PC board. They both run very smooth and quiet. I would like to add sound to these units but was not sure of the model # to begin trying to find the proper decoder to match the prototype sound, and or the right type decoder that will fit this unit. Be it a board replacement / or 8 pin …whatever. Also was concerned about speaker placement. This unit has metal ballast on front and back. Fuel tank area appears to be weighted also. 
Looks like making room in the rear is the best area to locate a speaker. So I took off the rear weight and shaved off the top 1/4 with a die grinder. 
Any help on id of this loco and or suggestions on decoders, speaker etc would be appreciated.
Your engine numbers are too blurry to read, but if you type that number into a search engine using the phrase such as “Athearn HO xxxx” it may tell you exactly which locomotive you have.
A LokSound Select would be a good choice of sound decoder, but as you already know, finding a place for the speaker is going to be problematic. The speaker that comes with the LokSound Select decoder is too thick to fit in that area.
You may need to completely remove that rear weight or cut it in half.
First, a question - Are these Athearn or Atlas engines. The old Athearn ‘BB’ engines did not have a weight over the gear box, or an electionics board over the motor. These look like an Atlas U30C model.
I would suggest looking at the ESU or Tsunami web sites. You will need a sound decoder with sound files for a General Electric ‘FDL’ power plant. The speaker will need to be under 3/4" wide to fit into the car body, and you may need to remove part of the rear weight to make room.
Jim
I agree with Jim in saying that these locos are Atlas U30C’s. Look at the bottom of the trucks, they may say Atlas China or something like that.
Jim, Thanks for the reply… Just thinking about it, I do think they are Atlas units. I was thinking Athearn… Thanks for jogging my memory. My mistake. Not that familiar with his model of loco as prototype or HO. I will take a look at ESU and Tsunami. Cacole… Good suggestion on using the road number for a model # lookup. Thanks for the advice. Bryan B.
Yup, those are Atlas, the motor and the two seperate weights are the giveaway. A Loksound Select Direct would repalce the factory board and solve the decoder problem. There might be enough room now that you’ve cut some of the weight down, or you might have to cut it down some more. You want the largest speaker and enclosure you can fit in there, for the best sound,. Loksound has new updated recordings of GE locos, and superb motor control.
–Randy