Problem with doing this is how is your truck setup and what are your end goals with it.
There's really 2 aftermarket manifolds that'll work without modification. 1st being 2bbl mopar m1 (no longer produced) and the Hughes Airgap. Airgap is a rebranded edelbrock piece with injector bungs drilled in. Both are great and perform virtually identically. That being said, without headers, exhaust and tune you'll notice a large lack in lower rpm power. You'll make more power but it'll all be shifted into a higher rpm range. These trucks are 5500+ lbs empty and the keg they came with does a good job at what it was designed to do.