@brianel_k-lineguy, you make a great point that the Lionel may not do the best job of highlighting what is and isn't DC compatible and that there are many nuances to the DC discussion. However, I ask you to find anything in Lionel's, Marx's, Ives', MTH's or any other major 3 rail O gauge lineup (beyond the rare outlier DC starter sets from ~40 years ago) that is NOT AC compatible.
No argument here!
I will add, we often read some negative comments about the DC only train sets first introduced by MPC and then continued for a while during the Kughn ownership of Lionel. BUT the worst thing about those sets was the TYCO copy of the DC power pack that came in the sets. It started with a minimal 6 volts to the track, making it impossible to run the engine only without speed demon, jack-rabbit starts. If you run those engines with a better DC power source that starts with a lower start voltage, you can make those engines run slowly.
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Manny, since you're on a budget, I would really strongly suggest you consider one of the Lionel starter set 4-4-2 steam engines. Very similar looking to your current Scout, but much improved. With a DC motor that will run on AC or DC, you can run the engine on DC, and then blow the whistle by hitting the direction button on your DC power pack... this will not affect the running direction of the engine.
The 4-4-2 starter set steamer was made for a good many years and was the best selling item in the Lionel catalogs for all those years, so it is a very common engine. Meaning parts are available. The motor and the smoke unit are both common and available parts. A with a little searching, you can find a good one for under $50.00. I've paid as little as $35.00 for one in perfect operating condition. Usually these are priced better than the Bethlehem Steel 0-4-0 I referenced above, or any of the other road names of this particular engine.
And using the Lionel Premium smoke fluid is a huge improvement in smoke output versus the regular smoke fluid that came with the sets.
The newer ones have an LED attached to the smoke unit instead of a socket and snap in light bulb. There were also some early ones made in the late 1980's-early 1990's that came with as non-whistling tender (those are usually less money). The only other real variation in these locos was visual: Some had a water heater in the shell casting, some had molded-in handrails, others had separate handrails. Some of the later issue versions from the late 1990's into the early 2000's had more complex paint schemes.
But in summation, they are reliable, well running locos for the money. And because of their large and lengthy production runs, they are affordable and parts are available.