fuel gauge ohm.'s for a 1966 c10?

[xratt]

i was getting ready to buy a 0 - 90 ohm. sending unit to mount in my aftermarket bed mounted tank, to work with my stock fuel gauge in the dash of my 1966 C10. Then i ran across some info about 2 different ohm. ranges for stock gauges. I know the stock gauge works, turn key on and its says full, ground out sending unit wire and it says empty. Just dont want to buy the wrong sending unit. And tired of getting stuck on the side of the road with my little gas can.

thanks for your help