it wil read a speed in neutral, and second is the nearst gear to the running speed on tick over that is why you can get it with out grinding if you bring up the revs a small bit leave it reving for a sec then you will get 3rd with out grinding, id say personally its either your diff, prop shaft or output shaft from the box, i was standing right on the corner when she let go was a good oul bang
iv no problem getting the gears i was purposely trying to grind them purely to see if they where still there, if you get what i mean, but not able to get 2nd to grind