fuel Sending unit OHMs!!

[2low72]

I know that our trucks sending units is 0-90 ohms (correct me if i'm wrong). The previous owner installed a mazda gas tank under the bed and the gas gauge has never worked right, but I also just found that the grounding wire for the sender was broke. My main question here is: could there be any chance that the mazda tank sending unit is the same and it just needs grounded, or am I screwed and will I have to buy a blazer tank to get the gauge working right?? Thanks