The thickness of shim you require will depend on your IRD / Transfer Box. Generally the early IRD units used a 0.5mm thick shim, these are the ones which are most likely to be destroyed when an IRD has a problem.
Freelander 1 IRD Transfer Unit Oil Seal Set Land Rover
Freelander 1 IRD Bearing Transfer Unit Rebuild Repair Kit and CWP Land Rover
Freelander 1 IRD Oil Seal Pinion UNG100060L Transfer Unit Land Rover
Freelander 1 IRD Oil Seal Transfer Unit Side Seal Set Land Rover
Freelander 1 IRD Oil Seal TRX100170 Transfer Box Unit Land Rover
Freelander 1 Axle IRD Bearing Differential Rebuild Repair Kit Land Rover
