Last summer I put a 5.9 from an 01 into my 79. I must say it was a pretty easy fuel injection swap. The only thing that I haven't got hooked up is my fuel gauge. I used the tank and sending unit from the 01 as well. I tried to just wire it like the original but it isn't working. The original gauge I know works cause I can make it sweep. I guess my question is there a difference in resistance between the 01 and 79 sender. I was thinking they were both 0 to 90. Also I'm thinking of just going with all aftermarket gauges since my temp, voltage, and oil are aftermarket. I'll just buy the fuel gauge and speedometer but I am looking to figure out this sender resistance thing so I know which gauge to get. Thanks in advance

Till the mid 90's or so, stock gauges were 10 full and 73 mt. Not sure what the 01 is but not likely 0-90, that's a GM scale and backwards from Mopar.

Yea I knew it's not exactly 0-90. But there seems to be two choices in aftermarket gauges 0-90 which should work for the 79 but not sure on the 01. The other choice seems to be 20-220 I think. Just not sure which one will go with the 01 sender without pulling it out and measuring the resistance.

From the '01 manual...

DIAGNOSIS AND TESTING - FUEL GAUGE SENDING UNIT

The fuel gauge sending unit contains a variable
resistor (track). As the float moves up or down, electrical
resistance will change. Refer to 8, Instrument
Panel and Gauges for Fuel Gauge testing. To test the
gauge sending unit only, it must be removed from
vehicle. The unit is part of the fuel pump module.
Refer to Fuel Pump Module Removal/Installation for
procedures. Measure the resistance across the sending
unit terminals. With float in up position, resistance
should be 20 ohms +/-6 ohms. With float in
down position, resistance should be 220 ohms +/-6
ohms.

Awesome thanks a bunch I searched all over the net for that simple spec. I just hadn't had time to dig my manual out thanks again.

I dont know when they started, ir if it will make difference for what you are doing, but since the mid to late 90's the fuel sender ran to the JTEC/NGC which then told the gauge what to read.

It won't matter in my application because I'm not running the sender through the NGC controller. It will be a standalone circuit similar to the stock 79 setup.