To work on my gauges I took my car cover (yes my truck has a cover) and wadded it up in the foot area of the truck all the way up against the firewall. Then I would lay out all my tools, hook up a light and lay down on my back and try to get as comfortable as possible looking up at the dash. If you have to hold your neck up at all you won't last two minutes. Make a pillow area.

In your case I hear you need to check all your grounds. If it is the gauge, I got a temp gauge from Mothertrucker and it works great and matches the rest in age/looks. I am sure he could pull a fuel gauge as well.

It really ought to take only an hour or so to change the gauge.

54 3100 with 235
62 flatbed dump C60 with 261