On the early vans i believebelieve the numbers were for the length of the van not the tonnage tho i could be wrong. On a 100 series the side door was right next the the passenger front door with only a pillar dividing them. The 200 series there was a side wall panel about afoot long between these doors insted of just a pillar. The 300 series had this side wall, and the back was extended an additional 1.5 feet. The 300 series was called a maxivan.
If you look at the second pic in this thread you will see a small window behind the drivers door. This is that one foot space before the main windows making this sportsman wagon a 200.