Temperature sending units

Working on a 95 FLD120 with a 6NZ cat. The overtemp sending unit went bad, and I haven't been able to find a replacement. Also had some issues with the automatic fan switch, so updating that. The overtemp switch is on the right top rear of the head. I added a "T", and put in a new 225 degree switch for the overtemp buzzer, and also a 195 on 185 off switch for the fan. I know that the ECM is programmed at 217, but at the moment, that rating was all I could find. Tested everything by jumping the switches, and all worked as it should. I fired the truck up, and let it run up on the temp gauge. Went almost to the red on the gauge, no buzzer and no fan. Again checked to make sure everything was wired correctly, fan kicked on, buzzer works. Sender for gauge had been replaced previously. Engine doesn't seem hot. I'm thinking of installing a manual gauge for my piece of mind, but wondering if the actual gauge is bad. Any advice?