My observation so far of these vans is that if the filler neck is before the rear axle then it is the small tank, for the tank is long and narrow. If the filler neck is after rear axle then it will be the 35 gallon tank, for its width is at or near the length.
Besides the filler neck postion another way to quickly tell is by where the spare tire is located. Is it under the van, then small tank, is it inside the van on the right hand side, then the large tank.
Last edited by Mobile Auto Repair; 08-30-2008 at 07:31 AM.