What I find an interesting point in the hobby is the extensive reuse of tooling and molds in models, especially plastic.
Bachmann…GS4 is old lionel HO mold…other 4-8-4 design (not the NYC one) is also.
Freight cars from them, some are lionel…
Life like…their non-p2k stuff is mostly old varney plastic stuff…box cars and stock cars are very noticeable
Model power…old marx molds of all things…the older bay window caboose and the short high side gon come to mind…
IHC, Tyco, Mantua.
The cab mold for their big steam models
IHC, 4-6-2, 2-8-2, 2-8-0 maybe even the 4-8-2, I forget old tyco molds
Mantua…every non 4-4-0 diecast
Tyco…see mantua
They all use the dwarfish little cab from the Chattanooga choo choo 2-8-0/0-8-0 mold
Something interesting…IHC’s new 4-6-4, front end looks like the old lionel/Bachmann 4-8-4
I am sure there are many more…I just forget them. These stand out because its hodge-podge, not that the company was completely bought by another company
Also, some F units, boxcars, tank cars and hoppers use Marx tooling. I collect Marx (O and HO gauge), so I’ve always been intrigued by this. It’s sometimes more than just the tooling that’s the same. I have a Lehigh Portland cement hopper car by Model Power that is exactly idenatical to my Marx one. If you put them side by side there’s hardly any difference. I’m not sure about other cases like this, though.
Mehano uses some of the Tyco tooling. Especially noticeable are the familiar Tyco style of cabooses.
Many of the brands familiar to you in the USA are just importers - they don’t own the factory or the tooling.
Lionel contracted with Kader Industries (Hong Kong) for the 4-8-4 and other HO items. Kader owns Bachmann…Thier contract undoubtably specified ownership etc.
All of the Tyco stuff made outside the USA was contracted…
Atlas contracted with Roco for thier first HO diesels: the GP38/49 SD24/35, FP7 and the Alco switchters. Later they contracted with Kato for the RS3, RSD4/5, RS1, RS11, RSD12, C424/425…
Over the years, the contracts have changed, with the importer now owning the tooling, so that they can move it around to different suppliers; like Atlas did with the RS3, etc.