AHM offered the Rivarossi O scale line, from the late 1960s to the mid 1980s. I have a German catalouge of Rivarossi, copywrited 1986, that shhows the “extent” of the line. It wasn’t much.
They made a kit and built up IHB 0-8-0, ICRR 4-6-0, a European 0-6-0 diesel “critter” a “GE” 4 wheel switcher (which appears to be more of a G-narrow 1/24th item) and the F-M C-liner.
Motors were a problem, as they used (by O scale standards) very small HO scale sized 3 pole motors, and they do not pull very well. That, by the way, is an understatement! The C-Liner uses a horizontal 3 pole truck mounted motor that drives the rear truck only. It is very prone to overheating. I have seen these converted to Weaver horizontal drives, and I saw one at a Timonium show that had an All-Nation drive under it. IRRC, All-Nation offered replacement drive kits for these units, but the drive cost more than the locomotive.
The cars that AHM offered were (In this I’m only referring to the American prototypes,there were European prototypes too, German, French, and Italian rolling stock were offered by Rivarossi and Lima) a flatcar with a crate on it, a “coal” filled gondola, a plug door reefer, a 40’ boxcar and a bobber caboose. The cars are a bit on the low-appearing side, compared to contemporary Atlas offerings, and current Weaver or Atlas O.
By today’s standards, the cars and locomotives are a bit crude, but by considering the state that O scale was in during the 1970s, they were a welcome addition to the rosters of many beginners in O scale. Including myself.
As far as collectability, they are not really worth much, more of a curoiusoty that anything, values, expect to pay $5-$10 for the cars, $35-$100 (too high IMO) for the diesels, and more than $100 for a good IHB 0-8-0 that is powered. Again, IMO all over priced.
Also, be advised that all the AHM-Rivarossi O scale was DC, 2 rail as sold. If it’s got a center rail pickup