I'm thinking about finding a rail truck (I know about the gears) and curious if the decoder has a sound 'socket' or does it require a new decoder?

I almost bought that engine, but after researching around and discovering it didn't have a drop in sound module I decided to pass.  It was a great price though.

Not really, but thank you.  I have all the documents.  I'm interested to know if the 'complete chassis' purchased through the parts store has all the gears in the gear box.  It doesn't say what it actually includes, and there is no picture of the bottom of the unit.

Same here.  My wife loves the fake snow, and after it getting wrapped around the axle more than once I have to go around with a scissor and clean it up before running the trains every year.

Curious if the gearbox in the chassis has all the gears and just needs the drive shafts?

https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=71_124&products_id=419

From memory, you should be able to carefully remove the ladder from the holes at the bottom of the ladder in the floor of the caboose.  Then when you pop off the roof it will come along with it and you can then remove it from the holes in the roof.  You can also leave it in place and when you pop off the roof carefully slide it out of the holes in the roof, but that's harder.

BTW, I've broken a ladder.

Is there a sound module available for the 28657 4-6-0 loco, and does it plug in or require wiring?

I'm late to this thread, but will reply anyway.

LEDs will flicker just like a regular bulb will, but if there is a capacitor already in the circuit then the LED may draw less power thereby not flickering as much or as soon as a regular bulb.

I have found that even circuits that include a capacitor usually still flicker, so I have begun adding a cap to all my lighted cars.  100uf - 1000uf if you have room to have a cap that big.

You can also buy LED strips on ebay or amazon to replace regular bulbs, or just use discrete LED's, either way.  If I add LEDs I included a full wave rectifier.  I use DCC, so a full way isn't necessary, but it will be if you use DC.

ADDED:  Here's an LED strip, but you can also find warm white.  https://www.amazon.com/gp/product/B00HSF66JO/ref=ox_sc_saved_title_9?smid=AAF37WJS3P6BT&psc=1

Added again:  It took me some digging, but I found a place where I purchased bronze material to fabricate wheel wipers so I could add lights to cars.  http://www.rodmiller.com/parts.html#wipers

I see the shay trucks are in stock, I just ordered a set

I've installed sound in 2 railbuses.  I wrote about it here:  https://www.modeltrainforum.com/showthread.php?t=112186

ADDED:  I used the soundtrax 885004 and the soundtrax sugarcube speaker 810154 which sounds much better than a 3/4 inch speaker that I also tried.  I listed all the details in that thread.

Would like to get new shay trucks... will they be re-stocked?

Is the switch manual, remote or DCC?

Do you have a multimeter?

Is the headlight capable of being dimmed?  I see CV 49-50 shows configuration for dimable lights, but I can't seem to figure out how to enable it.

I'd like to dim the light all the time without using a function key, is that possible?

Thanks for the information.  Those San Juan trucks don't have power pickups included, correct?  Can you point me to a resource showing how to make the bronze pickups?

I see there are replacement trucks for the passenger cars, but I would like to add lights to un-lit caboose and would like to buy replacement trucks from a lighted caboose.

Are there any of these available for sale, or has anyone seen anything available somewhere else?  Would HO trucks fit On30 cars?