Tesha

So, I’ve got a couple questions in regards to my baby. I’ve got a 1989 F150(4x4). Awesome truck, and really has never been a problem for the 3 years I’ve owned her. I was out camping last weekend and just about 5 minutes before we got there I noticed a light grinding noise while in neutral ( forgot to mention she was a standard). We unloaded the truck and I took her out for a quick rip down the road, both 1st and 2nd had a slight grind. I parked her immediately to ensure I could get home. My first thought was my transmission is going. I've never experianced any problems like this so I'm quite lost
Anyway we’re driving home and I’m doing what ever I can not to switch gears. I had to pull up to a red light, and tried to go again and I realized I was stuck in 4th gear. I was able to get her into second gear and pulled over. Again I tried to get her into first gear with no luck and alot of grinding. Instead of really messing things up I called a tow truck and was towed the rest of the way home. So I checked every thing over and saw nothing out of the ordinary. I think I might have pin pointed it to either the throw out bearing, clutch plate or the tranny went. I was wondering if anyone might have any ideas for me? I’m wondering if I should throw a crap-load of money into her, or buy a new one(not new, but another used one). Tough call. Any advice is appreciated. Thanks.