The Felpro is the one you want for sure. It fixes the issue between the Vortec composite manifold and the heads that causes the leak in the first place.

My dad got 300,000 miles out of the spider injector on his 4.3L S-10, but it sure ran a lot better when we replaced it. But I wouldn't mess with one that only had 100,000 miles on it.

When you go to seal the intake valley against the manifold, don't overdo it with RTV. It just takes a 1/4" bead.

There is also a torque pattern you need to follow when you snug the manifold down, be sure and do that properly.