[truckster]

Mine is a 72 4WD Blazer. I have 2.5 rams horns. I'm pretty sure I bought them from Speedway Motors. They're a perfect fit and I didn't do any grinding on the frame. For my application I used the straight-down manifolds, but I don't know how those would work in your truck.

However, any stock SBC manifolds should fit the Vortec heads. The exhaust ports are slightly different, but the bolt pattern is exactly the same. You might need to chase the holes in your manifold. Your problem might be rust in the bolt holes, or it's possible your manifold has warped.