Sam
The groups in the past were in regular direct contact with the late Capt Joe Eastwood BEM.
It would be a good idea perhaps, to try and make contact again where possible?
The chap in California was at one time in regular contact with Dennis Laverick. Their are certainly a number of photographs somewhere on the legacy website sent in by the chap (Chinese name from memory). He regularly attended cavalcades in Los Angeles, where he showcased the Ferret Scout Car. Again, he was at one point in contact with Colin Boutty (REME attached to 1LF), who used to service the Ferret.

Sadly as folk passed, contact was lost with these people. Their is certainly a photograph somewhere on the legacy website of Colin Boutty with the Ferret, when being serviced.