I have a 1988 F350 with 7.3 diesel (no turbo) with an automatic transmission. This is an old state salt truck with a dump bed and only 69,000 miles. The transmission started seeming like it was straining to engage, so I changed the fluid and filter and added Lucas transmission additive. The transmission is still acting up. With any type of load, I have to floor the thing to get it to move at all and you can smell transmission fluid. Once you get up to about 45, it rolls along although I am hitting 3800 rpm at 55 mph. The transmission selector looks like it has the D with an O around it meaning overdrive, but it has never hit a fourth gear since I have owned it (which is not long). It also takes a long time to go into reverse no matter if I have a load or not. I am not familiar with diesels or transmissions, so any thoughts on this would be much appreciated. I bought this as a farm vehicle and it might move once a month but when I need it I need it.
Also, it will not start unless it has been plugged in. It can be 90 degrees outside and when you turn the key to warm the glow plugs, all I hear is a loud click out of a box to the back side of the engine (under the breather) that has a bunch of wires going to it. It will not start. As long as it has been plugged in, even on hot days, it fires right up.