Fuel gauge wiring question

Update:
After having followed the great advice from members here, I got the replacement fuel gauge modified and a new RTE voltage regulator installed, and also powered my new in dash factory tach with the extra 12v spade, very handy indeed :) I also checked and I was missing the ground strap back at the fuel tank, which I purchased new and installed.
Its all working as it should now, thanks to all for your help and advice.
*CHEERS*