Originally Posted by
jonnyb
Yup - bulkheads in the p-bodies are a unique animal in that they're not bulkheads at all - they're just a bunch of smaller connectors! The best part is that it seems like every year they made changes to all the little connectors, so you can't even swap from one year p-body to the next without having to rewire under the dash.
Your 90 p-body harness will not plug into the 87 dash/bulkhead, so honestly, I would go with the spirit R/T harness. That way the entire engine side is done for the T3 (spirit and shadow have exact same engine bay so everything fits plug and play) and all you will have to rewire is the connectors under the dash. Oh wait, actually, I just remembered it's an 87 csx - I think the headlights might be different so you may have to swap a few connectors to get that to work, but still easier than changing your p-body harness to work with the T3.
I'm doing this same swap right now, except I'm doing it in a 91 shadow (and I'm going to use the spirit dash and wiring as well because I like to complicate things...LOL).
Jon