Can't you drill the hole needed if you have the other version? It looks like that's the whole difference to me. It's been a few years since I seen mine in the shed.
Hey lone wolf, I don't have any pictures of the original 86 manifold for reference, unfortunately, but it had the o2 hole and mounting holes w/ studs from the factory, the shape is also different than the 88 manifolds I have currently. It doesn't look like it would be easy to retrofit. I swapped to an 88 engine and wanted to use the newer 88 harness with 4-wire o2, but it looks like the harness has some shorted wires (code 14 IgF signal issues) inside. Also, I believe the kick panel in my 86 chassis doesn't have the space for the starter relay. I have the original 86 harness and the car was starting fine with the starter relay mod. Not sure how I'd accomplish this even if I could get the '88 harness fixed. I'm guessing the wiring to the kick panel has extra wires for the relay receptacle which I didn't think to grab from the car I got the newer engine/harness out of.
