I tried the TS-6 sending unit noted above, checked the gauges for proper grounding, tried the second gauge that I have and still could not get a reading on my old 6v gauge. Power to the gauge after the ceramic voltage reducer was 5.8 volts so wouldn't think that would be the problem. Finally got aggravated and put after market temp gauge under dash. No modifications were needed to mount the new gauge and sending unit, so can work on getting old gauge working properly later. The maintenance manual for 1947-1954 GMC Models 100 thru 400 shows that The electric type gauges were used on Series F350-24 and all other series using the capillary type unit. My truck is a 150 series so not sure if someone modified or just came from factory that way. I had gauges from two different 150 series and both were electric temp gauges. The manufacture ID plate shows both vehicle were made in mid to late 1949. Right now, I have a working after market temp gauge and will work on old gauge/sending unit later. Thanks to all for ideas and help.
1949GMCjwc
Willie
