When my manifold cracked I got a Dorman manifold from O'Reilly. It came with a lifetime warranty, which was good because it cracked after a few months. They replaced it with another Chinese made manifold which also cracked after a few months. In the end I returned the replacement for a full refund and ordered an OEM manifold from g1parts. It was much more expensive (~$200) but it hasn't cracked in a couple years. I agree that a used manifold is probably not a good idea.
I had to replace the exhaust manifold on my '95 . I used the dorman manifold and ran into a few problems. First buy the OEM lock nuts and install the new mainifold with them using the correct torque. Be careful attaching the collector, my casting wasn't machined very well and the shallow threads pulled right out, and I had to repair them with a helicoil. My Dorman has been on my van for over a year and hasn't cracked yet.