also could be the clutch or the throw out bearing, but my bet is it's definitely is in the linkage train. Check one of the rods, that happened to me on a '73 Z28, nothing but first gear, had to drive it 30 miles, in MN, in dead of winter to get it to a place where I could crawl under it and jam it back into place until I could get it into the shop. Could be a cotter pin fell out.