One of the main things you may notice if you do a transmission swap in a 420A powered car from automatic to manual is that your speedometer doesn't work, your car has a 6K rev limiter, and your reverse lights don't work There is a solution. To solve the rev limiter problem, simply use a manual transmission engine computer. This will raise yoru fuel cut to 7200 rpm and your ignition cut to 7800 rpm. To fix the reverse lights, simply get a harness plug for the manual transmission reverse switch (it is located near the front of the transmission) and run both wires to the 10 pin harness that was originally hooked to the front of the automatic transmission. One wire should be run to pin 1 on that harnes (black wire with a white stripe.....goes to the reverse light fuse) and the other wire should be hooked to pin #6 which is directly below pin 1. Pin 6 has a red wire with a blue stripe coming from it. This should get your reverse lights working again. To get the speedometer working again, you will have to get the factory plug from the M/T speed sensor (might have to get it from a junk yard) and you will need to run the #3 pin from the harness to pin 66 on the lower ecu connector. This will be a yellow wire with a white stripe. This wire is hooked in parallel with your speedometer and should still send a pulse signal to it. the middle wire from the speed sensor should be sent to pin 43 on the lower ecu harness. This will be a black wire with a green stripe. This supplies an internal ground for the circuit. The #1 pin from the speed sensor should be run to pin 44 on the lower ecu harness. This is a solid yellow wire. This supplies 8 volts to the sensor, which is the normal operating voltage. DO NOT SEND 12V TO THE SENSOR. This system works because the auto transmission computer takes signals from the intput and output speed sensors and converts that to relative speed pluses that the engine computer and speedometer can use. Without the auto transmission, the EATX-ECM has no output to the gauge or ECU. This electrical re-wire should fix this problem. Pin #3 on the speed sensor should have a little more space between the center plug than pin #1. To restore cruise control and b able to start the car, you must hook up the clutch pedal switch. the black wire with yellow stripe from the 10 pin harness used for the transaxle range switch should be located in pin #5. This wire should be hooked up to a clutch pedal switch that is grounded while depresed.
Thanks for the above Armond. I'm throwing this here since I can't find it referenced on the site. If you would like to read more of Armond's stuff head on over to www.armond30.com