I have an E150 1984 with (of course) a 4.9 l (300 cu.i) L6. The problem is this; it appears to have an advance (timing issue). The vehicle's distributor (carburated)has it's spark control unit ( a 3"-square box) on the side of it where, along with the cable harness, is a connector that disconnects the computer (located under the dash on the passenger side. This point is important). I've been told to disconnect this plug and time the vehicle at an idle, then plug this connector together and the computer SHOULD take over. Well, what happens is that the timing is thrown out so far that there is very little power and it pings like crazy. So what I've done is RE-TIMED it after connecting the computer. The timing advances somewhat but only if I race the engine with no load. Under load, it DOES NOT advance. For what I and some other mechanics can tell, it must be the computer as I've tried replacing the MAP (manifold atmospheric sensor), a device that affects the dwell setting sent from the computer to the distributor, I'm thinking by way of this plug that I mentioned before.
Sooooo, if it is the computer (remember I said it was located under the dash on the passenger side?), here is the number:
E4EF-12A650-Y1A.

So far, I've reached many dead ends by way of the auto wreckers. The dealer wants $325.00 (Cdn).

Does anyone have the unit WITH THE EXACT SAME number? If not, I was wondering if another distributor that uses the spark ignition control unit setup (the box that sits on the firewall) would work in place of?