Hello ranger community and thank you for your time and help!
A few years back my transmission was slightly slipping and so I replaced the filter and about 4 quarts of oil that was in the pan. That seemed to stop the slipping issue and I have had no issues with the truck until recently. I have also recently replaced the engine on my 02 4x4 4.0 xlt ford ranger.

A couple weeks ago I went to go to the store and all of sudden while on the highway the truck just redlined and It started to slow down. I'd push on the gas and no response even when I pulled of the road to a stop. I put it in park and tried drive again it had a little response then nothing. So I went to 1st and 2nd and they all work just fine so I limped back home in 2nd. When I got home I realized reverse also somewhat works.

I was told first plan of action should be drop the pan and see if there is metal in the bottom of the pan. I do so and it looked alright no shavings nothing really stuck to the magnet. The only thing was a little black sludge here and there but it looked like it did last time I dropped my pan. So I read some more and found out that it could be transmisstion valve body? The part that holds the oil filter? Well someone was saying that the gasket could blow and cause weird issues so I decided to go a little deeper.

As I was working on the car I decided to listen to the radio and so I had turned the key to the prestart position and then realized that I could have just made a mistake and turned it off almost immediately. When I went to pull the pan off there was about 3 more quarts of oil in the pan. So now my truck is missing about 6-8 quarts of oil. I don't know if it was from me truning the key to the prestart position or if it was because it sat for a week.

So I continue to take the valve body off and find out yea it is missing a sizable chunk in one corner of the gasket. Now I believe this might be the issue?

My question is how should I proceed. I have heard that you can destroy your tranny pump if it runs dry. So is this one salvageable? If so how should I proceed? Should I fill the pan up full and then try starting the car? I figure I should replace the gasket of course. I'm just not sure if I destroyed the oil pump or not. What else should I replace while I'm this deep into the tranny? Is all this stuff even worth repairing?

Again thank you guys for your time and responses ahead of time!

Ok first, your transmission holds a total of 10.5 quarts. A pan drop usually releases about 4-5 but after sitting and dripping, it could definitely reach 6+. When you re-assemble just fill it with 4-5 quarts, cycle the engine for maybe 10 seconds without starting it. (to do this press the gas pedal to the floor while cranking and the engine wont start). This will run the pump enough to get some fluid moving. Then start it and check the level after it warms up. Add as needed. When I did my valve body I think I used 7 quarts to refill.

The gaskets are a common issue. Make sure you replace it with a BONDED SEPERATOR PLATE & GASKET. Do not just buy the 2 paper gaskets. And be very precise when torqueing the valve body bolts. Do them all 3 times in sequence in increasing inch-lbs to spec. (80inch lbs sounds right but double check). There are different length bolts also, so be sure you're putting the right bolts in the right holes.

Unless you actually ran the engine with no pan on the trans you would not have hurt the pump. And you won't hurt it starting it up if you follow my advice above.

The new gasket costs about 25 bucks so is it worth it? Why wouldnt it be. Even IF the trans is fried you didn't waste much money to find out. And as I said the gaskets are a known problem up until around 2003 when ford switched to the bonded plate/gasket. You didnt mention the year of your truck so ill assume its an earlier model.

If you want, pm me and ill send you a copy of the pdf tech manual for your trans.