I got curious about this box van like truck which has two sliding doors on each side and two square doors that you pull open towards you when that tv show came on King of Queens where Doug works as a delivery driver using this kind of van. It's a typical truck that is used to deliver either mail or boxes around the city. I think it would look awsome in beamNG, doing some crazy stunts with the sliding doors opened. References: 1 http://www.hansenint.com/market/step-vans-box-trucks 2 https://www.indiamart.com/proddetail/box-van-20164555855.html
IIRC, these are known more often as 'step vans', as opposed to 'box trucks' or 'box vans' (like what the D/H series cargo box upfits are). I agree that one would be great for the game, as they're config powerhouses: parcel vans, ice cream trucks, SWAT vans, food trucks, etc. could be easily built on the platform, and from my limited research, might even be able to use the default H-series frame. That said, I would advise placing suggestions, even good ones, in the Vehicle Suggestions Thread.
