Most all US manufacturers at onetime or another built some kind of specialty tractor or packages that were used for power for other machines. Most of the specialty tractors were of a European design, some were changes made to standard production tractors. Even some were designed and built by people who thought they could sell their tractor. (Steiner for one). Most of the European designs were usually designed for vineyard, orchard or close area work. Yes there are some very useful builds that would could be used here but until they are imported the price is unreasonable.
US manufacturers used to make some very nice small tractors, but due to labor and material costs they found they could import Asian built tractors cheaper. After other Asian manufacturers found what the US manufacturers were doing they started sending their units here to. Some made out well some not so. Even the Russian's got in on it.
Now some people have a chunk of iron that has established dealers and kept there brand going, some had established dealers and folded, some found a marketing firm to sell and have no support. As I call the a "one time use" use it until it breaks.
Some of the specialty tractors were only marketed in certain areas and were not advertised out of that area, so most people were not aware they were ever built.
Packages include JD 50 for Barber Greene, MM packages 78, 79, 80, 81 for West Corporation on the Sky Trak, Oliver made 770 and 880 series for Lull Corporation for their brick lifts, I know the are others I don't know about.
Specialty tractors were as I said before were often made for vineyard or orchard work. Versatile made a bidirectional tractor that Ford got a hold of.
Just remember most of the European designs are good for the use they were designed but we Americans often want to do more with them than what they were designed to do.