Wow I missed some of these replies. They will help.

Quote
As for your guage reading I would bet all of next weeks glazed donuts that you have a 12 volt replacement sender in your gas tank. While 6 volt senders work on 0-30 0hms 12 volt senders work from 30-90 ohms. That is why everything is reading full all of the time...the bottom of the 12 volt scale is the top of the 6 volt scale.
This might be likely as it seems the tank and sending unit look new. If it is, can I do something about it? Or do I need the change the sending unit to a 6v?

Thanks.

54 3100 with 235
62 flatbed dump C60 with 261