Normal auto BA9S bayonet type LED bulbs are polarity sensitive and will not work in a Commando with a positive earth system.
Auto LED bulbs are designed for negative earth systems. You need to find a supplier that can sell you LED bulbs for positive earth systems or change your instrument bulb holders to wedge type fitment.
If your commando had W3W (504) wedge type bulbs fitted then you could fit normal replacement auto LED bulbs. To change the polarity just move the bulb half a turn in the bulb holder until it lights.
Obviously not possible with bayonet type bulbs as they are earthed through the bulb cap and powered through the centre connector.
Hope this helps