It's just my opinion, but I would get the gauge with the higher temperature range unless the two gauges aren't even close in temperature range. Your tractor is old and could have a thermostat that was replaced several times or even missing and if replaced, not necessarily with the correct one. If your tractor does not normally overheat, pick a nice cool morning, run the tractor up to temperature with the new gauge, make a mental note of the coolant temperature when it stabilizes and use that as your standard. Of course if one gauge goes up to 280 and the other goes to 240 either will work because I don't think your tractor should be running that hot. In that case I would go for the 240 because an unusual rise in coolant temperature will be more apparent. What's the difference between the two gauges available?
