Reverse just stopped working in my truck. It's a 1992 c1500 w/t automatic 4.3L v6. I pulled into my friends driveway after a 200 mile drive and when I went to back up I couldn't. drive and overdrive are sluggish and weak but 1st and 2nd stll seem to work fine. I haven't taken it back onto the main road to verify though. What is the problem and how should I procede?

First thing to do is make sure your transmission is full of fluid. While you have the dipstick out check the oil for color and smell BEFORE you add fluid. If the fluid is a brownish color instead of pink or it has a burnt smellyour best bet will probably be a trip to the junk yard. If the fluid seems okay you can try changing the fluid and filter. When you do add a bottle of Lucas transmission with your oil .It helps. My guess is that you are probably headed to the junk yard. If you do make sure the replacement is the same length as yours or you will be rebuiding a driveshaft. I have gotten away with it being an inch shorter but that is pushing it. Good luck.