My milkman back in 1984 had a black WB one-tonner with a 308/Turbo 350 from new. They were obviously able to be ordered if you knew the right person, or a few were made using surplus bits, but they definitely did exist. From my recollection of my conversations with the milkman (and there were many!), he ordered it that way. I remember a full instrument dash, console and GTS steering wheel as well.

Just because a catalogue doesn't show a certain thing as an option, it doesn't mean you couldn't get it.