I removed the factory ECU and all OE wiring years back. This car has been an on going project and FINALLY getting tuned for the streets after about 6 years next weekend.

Anyway, it depends what all you need to still operate? Do you have emissions testing where you live?

For the alternator, since the stock ECU triggers it, you can get an old school Mopar unit that all it needs is 12v to trigger to the alternator to charge the battery.

I ran a 9v output for my MS1 ecu to power up the speed sensor so that would still work.

There is also a 5v output that powers the TPS.

Tach output installed on ECU to drive OE tach as well.

OE fuel gauge will still work hard wired from cluster to sender.

Everything else I ran relays for off of a universal junction block from Summit Racing ($50). Ignition, ECU, ECU controlled cooling fans, power windows, gauges etc.

Brake lights are hard wired from switch to lights, turn signals are hard wired from lever using a universal flasher unit and headlights are ran off a relay/switch. I will post up some pics of some shit I did soon, I will be at the shop working on it tonight...