Dear Len,
That was it. Against all odds, I did it and was a success. Thank you for your help!
Elnovato

Dear Bach Man and everyone,
I bought a sound value soundboard (and a speaker) to replace the DCC-only board on a Bachmann Baldwin Sharknose. The soundboard came with no installation (wiring) instructions. On the bottom it has some initials (HL+; HL-; S+; S-; RR; LR) on one end, and some others (RR; LR; M-; M+; BL-; BL+) on the other end. Could you please indicate where I can find the proper documentation to install the sound board? I looked in some places in the Bachmann website, but could not find the eference to the specific sound value board. The model is AE32029.
Thank you all in advance.
El Novato

The Athearn/Roundhouse streamlined cars look good on 18in radii. I think they are 72' long. I would love to buy full length, more detailed Bachmann cars (in my opinion they are better value than top of the line Walthers). Unfortunately all those require a 22in minimum at best (and some do not specify).

Walthers Mainline offers full length Amtrak (and other roadname) cars that run on 18in curves.

Thank you very much. I guess my question more specifically is if all HO DCC soundboards offered in the soundvalue locomotives (with AE320XX format) have the same dimensions regardless of the sounds associated with a specific diesel locomotive (say GP40 vs F7). I was planning to buy two of them to install into my Bachman GP40 and Baldwin Sharknose (DCC only) locomotives (in both cases along with the generic speaker available). But I wanted to ask whether they fit before buying them. I am aware that the sound effects vary from model to model, but that is less relevant for my purposes. Thank you again.

Many modelers prefer metal couplers as you will see in many videos. I have limited expertise on the hobby, but the EZ Mate couplers have worked fine in my layout.

I guess it depends on whether the couplers are truck mounted or body mounted. There are several videos on youtube that you can look at. The example below shows how to modify truck mounted couplers...

https://www.youtube.com/watch?v=xzkjxRoJUu4

After you move the black switch button sideways, you need to press it down for a second or two before the turnout actually moves...

You need a second (analog) power pack.  Look at the videos below (ignore banners in Spanish):

https://www.youtube.com/watch?v=yHdXXHxgNHA

https://www.youtube.com/watch?v=q3xkLj0HaJU

If I order a sound board AE320XX and a speaker #10080, do they fit into a DCC only GP40 without having to cut the metal chassis? Does the sound board fit on top of the chassis (I don't see why not)? Does the speaker fit into the fuel tank space in the non-sound locomotive? I saw both diagrams (GP40 DCC only and GP40 sound value) and it is not visually obvious. Thank you.

Thanks!

The trucks are riveted. The couplers have a tiny screw. I think I will look into a Kadee conversion and keep the original trucks. Do you guys see a problem with plastic wheels in general?

Yes, those were exactly the web links I found where I learned about the origin of the set. Thanks for sharing them!

The trucks are metal.

I am a rookie! The couplers are truck mounted...