The whole subject of Ives transition is a long and complicated story Chris! To really know the field and know what you're looking at, I would recommend the Ives Society website with its many articles and photo galleries, as well as some of the better books on early tinplate.
Ives had all their own tooling for their own designs, as did Lionel and Flyer. For example, Ives had their Wide Gauge 3236 locomotive, which was comparable to the Lionel 8e but was a distinctively different design; a New Haven box cab rather than Lionel's New York Central box cab design. When Lionel and Flyer took over the Ives company in mid-1928, the first thing the new owners had to do was to quickly gear up to fill Ives's existing orders for the Christmas 1928 season. One of Ives's biggest problems was that its designs, while quite detailed and realistic, were much costlier to build than Lionel or Flyer's versions. Also, many of Ives's dies and tooling were getting worn out and would have needed replacing. So to meet the deadline with no time to come up with new designs, and needing to save money at the money-losing Ives plant, the new owners substituted some of the cheaper-to-make Flyer and Lionel designs to replace some of the most inefficient Ives designs.
One of these substitutions was to use the Lionel 8e cab in place of the Ives 3236 cab. It was modified slightly to fit on the 3236 frame with the Ives motor, and special Ives brass plates were made for it. It was called the Ives 3236, but it now looked more like the Lionel 8e because it used that cab stamping. It's not the original Ives 3236, it is the later, "transition" Ives 3236 with the 8e cab.
In 1928 and 1929, most of the substitutions came from Flyer stock. The long low Flyer passenger cars from the President's Special were painted in Ives colors, and used Ives trucks and couplers on the Flyer bodies: these became the Black Diamond, Northern Limited, and Olympian Ives sets. Flyer also supplied the freight car bodies; so the Ives freight cars for 1928 and 1929 were Flyer freight car bodies, on Ives trucks with Ives couplers.
One modification was made to this lineup in 1929. The Flyer freight tank car was itself fairly expensive to make, with its big tank, brass bands, and trim. To economize further, Lionel contributed its tank from the 200 series tank car. This was put on the Flyer frame with Flyer brake wheel stanchions; but still using Ives trucks and couplers. So in 1929 only, this car had parts made by all three companies. The rest of the line continued as in 1928: Flyer body cars on Ives trucks and couplers.
For 1930, Flyer wanted out of the partnership, so Lionel was left to manage the Ives line on its own. So now Lionel provided the Lionel freight car bodies for all the Ives cars, mounted on Ives trucks and Ives couplers, and with Ives brass plates. This is also when Lionel substituted its passenger car bodies from its 418-style cars, making the Ives National Limited and Chief passenger sets: Lionel 418 car bodies with Ives trucks and couplers.
The next year, Lionel stopped putting these cars on Ives trucks and couplers: the freight and passenger cars now were pure Lionel cars, but just labelled Ives with Ives brass plates. These cars, though labelled "Ives", were incompatible with any previous Ives cars because they had the Lionel latch coupler.
And by the following year, the Ives name was discontinued completely, the Ives line dropped, and Ives was history.
This is just a rough outline, and there are a lot of details in the variations which can be filled in to this story, but this is why you come across so many different variations of the late-period Ives trains during the so-called "transition" period when Lionel was gradually phasing them out.
MTH has never reproduced the earlier, pure Ives freight cars; they were hand-soldered out of many pieces, expensive to make, and would be even more costly to make today. Since MTH was making the Lionel cars, and also the Flyer cars; and made Ives trucks and couplers for the Ives passenger cars, it was an easy thing for MTH to replicate the various "transition" Ives cars by combining these parts. Same thing with the MTH reproductions of passenger sets like the red and blue National limited: it used the tooling it had for the Lionel 418 cars, painted them the different colors, and used Ives brass plates, trucks, and couplers.
The same is true of the Ives 3236, for example: MTH has never reproduced the original Ives 3236 New Haven cab: but since it was already making the Lionel 8e, it was a simple thing to use the same cab with Ives 3236 plates and call it the transition Ives version.
david
