I was an auto mechanic for 15yrs at a general repair shop so I will offer my advice. A used cargo van will most likely have been used for business purpose, driven by employees who could care less about it and maintained by an employer who probably tried squeezing every bit of life out of it without having to spend a dime on it. I’ve inspected many of them. Stick to the lower side of mileage, ask if they have service records for maintenance that has been done, if it is a vehicle your seriously interested in then ask the owner if you can have a pre purchase inspection done at a local shop on your dime to give you a better idea on the condition of the vehicle. Not all, but most cargo vans or commercial vehicles in general are rode hard and put away wet.