I have (had) two tractors with ISO fasteners: M8 nuts with wrench size 14, where DIN (Deutsche Industrie Norm) is 13mm. M10 is 16mm, M12 is 18mm. (in DIN these are 17 and 19mm respectively)
These were a Ferguson 35 with the Standard 23C engine, and my Zetor 3011 of 1967 (even though it is model 1958)
This was because both America and Europe were going to standardise to ISO.... But America pulled in the turd... So Europe went back to DIN standard as it still is today...
So, America will slowly convert to DIN because fasteners are cheaper on the world markets, and because so many products are already engineered in Europe: Navistar engines by MAN, Paccar engines by DAF, John Deere builds for the world market so its metric, and so does CNH. All Japanese brands of USA built cars are metric... It wont be long till the only things Imperial are fasteners used in construction...
The reason that American belt trailers are converted to European SAF or BPW axles, is because no trucking company wants American axles, with imperial dimensions... So yes, we'll buy anything off your hands, as long as its metric...