I received four of these in the mail this afternoon (Posted on the 16th of Aug and arrived in Australia on the 21st...not bad!) and started looking through the usual references. The V12 vans are noted as being built with the sliding ventilators rather than the bonnets fitted to the V14 and V16. However, some were later fitted with the bonnets - at last according to photographs. But does anyone know when this was done from? The best date I could find is in the GWR wagon book (the big one!) where