T-5 repair?

You may be lucky to find your problem at the input shaft of the tranny..4th gear ties directly to it..(in case you didn't know) Your problem may be the syncro. & this is where you are lucky. Once you remove the tranny from the car, remove the bearing retainer and the input shaft will come out fairly easy. Do a search on the 5.0 section for a t-5 manual to help you identify the parts. I have located the syncro at a local transmission supply store here, hopefully you have one in your town. A transmission shop may be of help for the part. Also, make sure you have the right amout and type of fluid in it.

Good luck...Jim