[truckster]

I haven't used the other choices, but I can chime in on the Vortecs - I love them. For best results, combine them with a roller cam that can take advantage of their ability to breathe. Though there aren't a huge number of choices for an intake manifold, what there is works well. As far as cracking, I wouldn't put a used set with cracks on a rebuild, but I've never seen one with cracks bad enough to be the reason it was taken out of service.