Bumping this thread as i am starting to have this issue myself, except downshifting to 4th, 3rd or just going into neutral from 3rd. Clutch is completely engaged and i still get the grind. I did transf fluid swap about 15k miles ago with redline and hadnt had issues until today. Does anyone know if replacing trans fluid gets rid of this? Ive read that some people had synchros gone bad and others had transmissions replaced
