73 Duster after market fuel gauge with stock sending unit

I don't know for 100% that it is the guage...I just read that a risistor in the gauge frequently fails...The car sat in a WY junk yard for 20 + years...I removed the tank, cleaned it, and put in a new fuel sending unit before breaking in the new motor. This the fuel gauge worked for maybe 10 mintues during the motor break in (had about 5 gallons of fuel in the tank and read a bit above a quater tank) Then next time I went to move it, it was stuck on empty and hasnnt moved now in a year