Be sure to take the structural integrity of the shock mount into consideration. The ones on the D2 were never designed to handle a load and air shocks would be a constant load.

If you really want to do this right I would look into air bags where the bump stops are.

 

The discovery II I bought also has had the air suspension taken out and replaced with shocks

 

Those are Old Man Emu (OME) Nitrocharger > Discovery II Shock Kit - Front & Rear - Nitrocharger Sport - Old Man Emu / ARB

You can SEARCH the OME catalog here (the "Suspension Selector" is helpful)> ARB Old Man Emu 4X4 SuspensionARB Old Man Emu 4X4 Suspension