Maybe this will help.
OC-12 temperature rules:
140F-160F is ideal.
180F is getting too hot, and you'd best slow down and make crisper turns.
200F and you’re doing damage, you will be at210F shortly.
210F and if you're still driving the temp will runaway,
you must stop and get it back down to 180 or less.
IF 180 degrees F. is exceeded for fairly long periods, rapid deterioriation
of steering bands, drums, gears and bearings occur.
At 210F and higher, imagine how hot it’s getting at the
brake band/drum contact area...
[From the LMC 1200c manual ~1989/1990] Diff temp gauge:
This gauge registers the temperature of the oil in the differential.
The normal absolute maximum temperature (with DN-600) fluid during continuous operation is 180 degrees F. If the differential exceeds this temperature, stop the vehicle to permit cooling. If 180 degrees F. is exceeded for fairly long periods, rapid deterioration of steering bands, drums, gears and bearings may occur.
-Pat