Spectra or quanta??? Help!!

I just put a Spectra sender in my '67 Barracuda, connected to the factory gas gauge. The gauge remains pegged over full through the first 4 gallons, then drops somewhat linearly through the next 6 gallons 'til it reads 1/8 full. At that point, there are still 8 gallons of fuel in the (18 gallon capacity) tank.

The sender's approximate ohm range is 10 ohms at full, 80 at empty.

BTW, I would have responded sooner, but you did say you got all the help you needed. Then I decided to tell my story anyway.