Oh well had to ask. At least I have a photo of a stock 2421493 to help with my search. The original was replaced long ago, I get the linear vs no linear issue. the current sender I have reads full when the tank is full (18 gallons), 3/4 with 16 gallons, 1/2 with 14 gallons, 1/4 with 12 gallons and a little less than 1/4 at 9 gallons and stayed there for the next 100 miles till I ran out of gas. should have had 3-4 gallons still in the tank by my calculations. (I have checked with a dedicated 5V power supply and 0 to 100 ohm variable resister that the gauge and wiring from the sending unit are good ~75 Ohms empty on the gauge, ~23 1/2 on the gauge, and ~9 full on the gauge) Forgot to add that the grounding strap on the sender to fuel line is in place and good. I will point out that the windings in the top photo look to have a different pitch on the left side than the right side and that would give you a form of non linear sender. also the shape of the tank will effect the linearness of the readings as the tank will deplete from the top down and the A body ( dart) has a basically rectangular tank till the lower 1/4 to 1/3 then it adds the area under the spare tire which will deplete slower than the upper part from a level stand point. Just my 2 cents. I did find the last ( what I was told by the dodge dealer) 4051004 NOS sender in the dodge factory parts system, hope it works properly, will know next week. In the mean time I will be keeping my eyes out for a NOS 2421493 or maybe a wrecking yard OEM that can be repaired by one of the links you all provided.
