To start, your truck was not "restored" if it has rear disc brakes, it was modified.

As for the calipers being on opposite sides, My F-250 came that way so I have no doubt many GM vehicles 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.