Unusual Marx pieces. Are they documented?

never can tell with Marx. maybe they just reused some leftover/not good enough stock? Like the cabooses with the litho on the inside?

El Classico posted:

I got these Marx trains from my grandad about 6 years ago, and have had them since then. The engine is a heavily modified 495 that had a black boiler originally, with original maroon sideboards; cars seem like standard 555 and 556 cars, but a look on the underside shows a brass coloration on the underside of the frame, inside of the caboose, and the doors on  boxcar.  It was brought to my attention in another thread that these are not necessarily common to see; have they been documented before? 

Brass under frame on 556

I have a Marx 556 caboose that looks brassy on the bottom of the frame. I think it's just a factory clear coat finish over bare metal that has yellowed with age. It looks somewhat greenish in this photo, but in daylight it has a yellow tint. Common and typical, I think.

Have you tried testing with a magnet on the suspected "brass".  I also have Marx rolling stock with the "brassie" coloration, never gave it much thought.  Then, have other "not so well preserved" items that, true, are not that noticeably rusted on the bottom.

Jesse    TCA  12-68275

That brassy look is also pretty common, not sure what it is. Definitely not brass material.

Steve