When I first got my car I had the same problem. I knew 1st gear synchro was gone but 3rd started to grind also, took it to Ford and they tore down the tranny to find both 1st and 3rd gear synchros were shot. Before I didnt have the 2nd gear crunch everybody talked about, now I do but 1st and 3rd are great lol! Guess I cant have everything! Is it when you are shifting hard at high revs or just when your cruising around town?