If the truck has the stock 283 it should already have the 2" center dump rams horn manifolds unless someone changed them out for something else. The 2 1/2" Corvette Manifolds would also work well but are generally a little pricy.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine