P.S. If those studs in your pic are on the temp gauge, they are not for a ring tongue. You should not take the nut off IMO. You may need what I think I see in the lower right corner of the "Repair Components"/Temp sender unit lead repair kit" picture. I am pretty sure the "L" shaped Gray connector/contact set is for your gauge.
You can also see them in this pic.
http://www.trifive.com/garage/56%20Chevy%20Assembly%20Manual/12-4.gif

The Nuts I see in your picture are to hold the gauge meter onto the gauge housing. Those stick-up studs need a special connector as seen in my links. These are known as "pin grip" contacts/connectors. If you can somehow get a ring tongue to work, UP2U, could be OK.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn