Im in the process of swapping my 72 Malibu Sweep dash to a 72 SS idiot light dash. Question is, does the white resistor (I think its a Resistor) on the back of the fuel gauge need to be changed? I thought I read somewhere that I might have to. Thanks

Not that I know of. You may have read about the aftermarket tach/gauges conversion from SS idiot light. You use the resistor off the old large fuel gauge for one of the other gauges (can't remember which one but I think it was the temp gauge).