hey all. I have a 91 LS block but when i bought it, it had an OBD2 head of unknown year. Does anyone know what intake manifold I should be using? My car runs OBD0. I ask because i have never seen my intake manifold in any pictures online. It's stamped p-75 but the vacume ports are strange and i suspect they are hooked up wrong. Does it matter what OBD my intake manifold is or are they pretty interchangeable? I figured newer manifolds might have different vacume ports and such for more stringent emissions systems. Thanks for any input.