You don't say what year your truck is but your gauge probably uses a 30 ohm sender. The '60s Chevy car most likely did too.

"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.