The main difference between the DeLorean automatic and the later model transmissions is how the computer control the pressure modulating valve. The solenoid valves that control the gear ratio is simple and only an on /off issue. However, the pressure moduling valve is controlled by gear, rpm, vehicle speed and trans temp.(4 th gear). What is interesting is that the Ds computer fails in terms of gear ratio change and not pressure modulating valve control. ( From what i have heard.) However, gear ratio change is a pre programed into the Eprom in the computers. The only way the wrong gear gets selected or will not shift properly is that the input calling for a new gear is not seen by the computer (sensor failure) or the E prom's program has become faulty. This should be easy to test on failed computers. If it were the sensors(which is unlikely) connecting a new computer would not fix the problem. Therefore, the problem must lie in the Eprom program in the computer. Assuming the pressure moduling circuit is okay and can be accessed, this Eprom program is not all that complex to build and/ or isolate from the heat area of the transmission. In more recent cars the computer was located in the car to avoid heat related failures.. bob