Need at least 2 more pieces of info. Make and year of truck and an ID on the alternator. Different years grounded battery in different places. Some alternators use external regulators, some don't.

"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.