Ok when I bought this truck it didnt have reverse. Now I want to try to figure out why before dropping the tranny. It has a slow leak from the pan. The magnet is out of the pan and is sticked on the outside of the pan. I dont know how to drop the pan because the exhaust y pipe and crossmember keep it from coming all the way down and off. However, I noticed the tranny fluid was darker than usual. I added new tranny fluid and Lucas transmission fix and still had no reverse. I'm hoping my filter just needs to be changed and that'll fix my problem. I say that because RPMs slighty decrease when I shift into reverse, so I know the gear is engaging, which means it shouldn't be at fault right ? All the other gears shift just fine. When I'm on the highway, it shifts thru the rest of the gears. Can anybody elaborate this transmission to me and possibly tell me how to test it before i remove the tranny ? Also could it be a faulty TPS ? or bad booster valve ? I also have a video of the rpm shift to reverse and me driving using the engine break test.

 

I'm no transmission expert , but I understand that no reverse is quite commonly a cracked internal sun shell.