There are two head/port styles on the 409s. The truck engine should have the small port/bolt pattern as the 348/lower HP 409s. The high HP 409 heads have larger ports and a different bolt pattern. You can still find performance manifolds that bolt up to the 348/409 small port pattern, Edelbrock 7158 for example. You don't need an adapter with those.
To check fitment, you may want to look at the head casting numbers, and consult:
409 Casting Numbers for the specifics of the heads on your engine.
