I have a couple of spare stocks but there are differences between the very early model stock and the later ones. The very early ones did not have the bolt up through the (strengthened) pistol grip. On these, the rear of the action was fastened to the stock by a bolt through the trigger guard
Mk 1 and 2 Airsporters usually had 3 piece stocks but I have not yet seen one a Cadet Major

John