I saw an article in Australian Muscle car a few months ago on these vans and the Round Australia trial. The poor old Ford factory team only had transit vans and could not keep up with the V8 vans!
J rego plates were around in 77 as we bought a Hilux new and it had JFK plates and was purchased in Mudgee so the plates would have been hanging around for a while then being a country backwater.
They did have more than one according to AMC.