I got a really good deal on a 2-rail Weaver Troop Car and was able to slip some Hi-rail wheel sets into the trucks. Some Hi-rail wheel sets have axles that are too short; some don't. Also, the ends of the Hi-rail axles on mine were a hair too large; literally, a quick
Moto-Tool grinder trip around each axle end cured it. Zip, zip.
Maybe not relevant, but I then removed the bolster spacers and put in Weaver Hi-rail
couplers, as I don't use the wee couplers on my layout.
Note: I got a Big Box of Hi-rail wheel sets at auction a few years ago; the guy had them
left over from his 3- to 2-rail conversions.
I readily buy 2-rail cars (especially old, historically interesting ones from the 50's and
before) and proceed to convert 2-rail to 3-rail - undoing some of that 2-rail damage that
he did....!