Your panel is from a US GMC. Notice the 0-60 oil gauge. Notice the "fuel" gauge rather than "gas". And notice the electric temp gauge.

Unless it came from a '55 or later school bus it is 6V. To use the gauge you'll need a sender, which is just a variable resistor to ground, so voltage doesn't matter, and a reducer for the 12 to 6V on the gauge end.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.