or, you could also get a wiring diagram for the 94 and just add the 4 wires from your computer to the extra two injectors(2 signals and 2 grounds), and keep your old 3.9 harness. then youd only need to get a computer for a 5.2 manual trans 94 ram. I'd try car-part.com, they always have some listed at various lots around the country.
I'd just add the 4 wires, but if youre not comfortable with wiring, I'd just find a donor harness