IIRC all the GMC CCKW´s which were sold off from Netherlands Army war reserve stock in the 1980s had to have the instruments removed. As they were supplied under the MDAP scheme, they were formally handed back to the US Government on whose behalf they were auctioned off. Before the Dutch government was allowed to do so, they had to be be put back in serviceable condition, which included overhauling brakes etc. but also removing the radioactive gauges.
Attached goes a photo of a CMP Chevrolet C60L for sale at a dealer in the Netherlands. If you look closely you will see a yellow sticker over the main gauge which states "VOORZICHTIG RADIOAKTIEF" - careful, radioactive. Maybe for the UK MoD this is an acceptable way of managing the danger on your truck, at least until a replacement can be sourced?
HTH,
Hanno