Pretty sure the 307D is the van a couple of builder friends had, and i used to see a steady stream of them traipsing to and from the open air markets in Pembrokeshire - at one time they seemed like THE vehicle for the Market Trader.
I was told that as a platform the 307D was a steady plodder, but its main redeeming feature was being utterly bomb-proof and unfussy for starship-type mileages, pretty much regardless of how well (badly?) the beast was maintained. Sounds pretty good to me!