New sending unit in the tank and the gauge reads 1/2 when empty. Guess how I know? Gauge is original and this was the first it has had to register in 14 years.

Mike

That happened to my old '75 back in the mid '80's. It was a rusted fuel siphon tube in the gas tank. When it got to 1/2 empty, the fuel pump was sucking air through the rust hole.