Difficult one that one. Built after 1/76 the GMV should be de-rated for a XX7 Sandman (Passenger tyres) but wouldnt be for a XU3 Sandman (Commercial tyres).

So to prove it is an XU3 ute over an optioned Kingswood without the option code on the plates is very hard. Byron may have some body indicators but I doubt you could convince many from those plates alone.

Mauser