Older 700R4 vs newer 700R4

[mckpaul]

Got into my tranny over the weekend, pulled the valve body and cleaned it up, thought I might find a stuck valve, and replaced some of the springs. My truck isn't a daily driver, kind of a project for now. Been hearing a slight knocking from the engine on occasion. The '84 doesn't have an ECM, the only thing it has is the knock sensor system (EST?) and it's all been disconnected. In the back of my mind was hoping the knocking was related to that. Well, went out for a test drive after the transmission work. The transmission still had the same upshift problem AND got about a mile from the house and the engine died at a stop sign with a slight squeeking noise. Wouldn't turn over after that, strong battery, good heavy "click" sound when turning the key. It did finally turn over one more time and started for about 10 seconds and stopped again with the same squeeking sound, hasn't turned over sense. Have a feeling the engine's locked up now in addition to having a transmission that needs help.

Enough whining... so about my question. I know I can get another 305 or even rebuild mine if I want to, but as for the 700R4, it's the original one that came with the truck with the small input shaft. Looks like it's had several hands in it before, stripped pan bolt, one of the valve body bolts was stripped too, has a piece of stainless wire in the bolt hole. I was installing a shift kit that I bought that suggested enlarging some of the holes on the valve body spacer plate, some were already sloppily drilled out. Was thinking about going to a newer 700R4 when I pull the engine. But looking in the transmission book (700R4 rebuild book from a transmission parts house), there were about a dozen different wiring/switch setups for various valve bodies. If I get a newer 700R4 with the larger input shaft, even though the my wiring harness will probably plug in, wouldn't the newer transmission be wired internally set up for a newer truck with ECM? My harness has three wires on a 4-pin plug, in the book they all seemed to have that, but the switches on the valve body were different for the newer model diagrams. If I put a newer 700R4, will I have to modify my wiring, or possibly pull the pan on the newer 700R4 and change the switches and wiring on the valve body to match my truck? I want my lock up to work in a normal way. Was wondering if anyone had put a newer tranny in an older year model truck before.

I'm hoping to run across a running 305/700R4 combo maybe in a wrecked vehicle and get both together.