Jonny said:

I have determined that the fuel gauge sender on my '64 is busted. I have a 
spare, but is it neccesary to remove the entire engine and gas tank to
replace 
it?-----

yep-  and the gas  (h)eater  is in the way of taking the gas tank out,  so my
66's gas guage still doesn't work

 but don't get discouraged - think of it as a n opportunity to change your
main and oil cooler seals, hook up the thermostat,   check your clutch, throw
out bearing, and  trans boots and top the gear oil.   Take it to the car wash
first!