[MARKDTN]

If you want to buy a harness, I would buy a Howell or Street and Performance (not a Painless). You should not need a PROM unless you want to get rid of EGR. I would keep canister purge. There is no VATS in a TBI. The Stock GM TBI harness is almost plug and play. The ones in the vans are even better because they are long to put the ECM under the drivers seat. It should be pretty easy to use a stock harness and do a 4-wire hookup. That will place the ECM behind the glove box and take up a big chunk of space, particularly with a/c. If you did go with (long) aftermarket or van you could put the ecm under/behind the seat or in a console. You will probably want to use original manifolds and add an O2 sensor bung rather than try to use the later manifolds.