You need to provide some additional information on the year of your truck, and at least the make of the carburetor (Quadrajet, Edelbrock, Holley, etc.). All carburetors have similar functions, but how you adjust them depends on the brand.
Also, original Quadrajets were usually installed on a spreadbore intake manifold (the primary bore is smaller than secondary), while most Edelbrocks and Holleys are designed for squarebore manifolds (primary and secondary are approximately the same size) Unless you want to also change intake manifolds, its usually easiest to use a carburetor that matches the intake. Using a carburetor adapter adds more gaskets, and more potential for leaks.
Bruce