IH used two different gauges on the 560.
One was a Stewart Warner and I can't recall the other brand.
I was told by my machanic that the new STewart Warner gauge will not work with the old sending unit.
So to replace the gauge you have to replace the sending unit as well.
Kind of costly to replace.
I just bought a 560 diesel that the gauge doesn't work. My 560 gasser did work so I'm gonna take that complete unit and gauge and put it on my diesel.
The gasser is getting weak and I may part it out.
I need to get them both in the shop this winter and swap some pieces around on the two.