I don't think short-term the wrong fluid's going to cause any issue, but I believe merc-dex is the correct fluid (don't think Mercon V existed back in 95 and the owner's manual likely says to use plain old Mercon). Mercon V is full-synth (if I'm not wrong) and it supercedes the older fluids and is supposedly backwards compatible so Ford seems to recommend it for pretty much anything (aside from really old transmissions that take type F). Ford & GM won't license the Mercon or Dexron names for whatever reason so the aftermarket just calls it merc-dex. As for the wiring you're only dealing with about 4 wires of consequence. http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-CCRM-PCM-Transmission.gif You can trace those back to the ECU and check the resistance from the pigtail all the way back to the ECU with a simple multimeter. This diagram helps (a little, since only one of the 4 wires from above is traced to a pin on the ECU, you can find the others using the colors). http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif Make sure you're getting nice strong (+) voltage on the red wire, the other wires are all grounds so don't expect to find voltage (this is why checking your grounds is important). I'd suspect the white & yellow guy - the pressure control solenoid. That one could make the trans slip / not go into gear. The torque converter lockup doesn't sound like your problem, and you haven't mentioned shift issues so that's where I'd start. I'd probably run a replacement wire for white/yellow to test all the way from the ECM to the transmission myself. Your other option would be to have it towed to a good transmission shop for a diagnosis. Some places will even hook you up just to check it out for free. They can see what the electronics are doing and how the transmission is reacting and tell you if it's bad or if you have an electrical issue. Sometimes it's worth it to let someone else deal with it, especially if it can save you a bunch of hours of laying on your back.