I think the early 8V is all the same 2 piece design. the 90+(?) 12V use a 1 piece manifold with oblong ports & since the distributor location changed the flange is different in that area.
I just pulled mine off the other evening and I found it interesting how the PCV delivers to all 4 intake runners through little passageways cut into the flange at the upper/lower mating surface. but I digress...
something I had been thinking of - the 1.8 SOHC uses a 2 piece manifold as well. the lower portion is totally different as the head ports are spaced differently, but the upper half looks the same but with the larger TB opening & bolt pattern. check out the plenum gasket for the 1.8L:
that looks exactly the same as my Excel gasket including the extra hole for the EGR return port but minus the hole for the 8mm stud center-back. I'm thinking perhaps the 1.8 upper will bolt onto the Excel/CSM 8V lower & allow for mounting the larger 1.8 TB.
there must be someone here who has seen both manifolds that can either confirm or deny this possibility.
