I have a 2003 Ford E-250 3/4 ton van loaded with machines key blanks all kinds of inventory and tools. I do not know the weight of my van and I am not sure if you need shocks specific for my application. I just don't want to replace something a couple years down the road when I could have spent a few dollars more and did it right the first time.
You can get good heavy duty shocks for cheap, but if you want something that will last under heavy loads, it's worth the extra money to buy premium shocks. For your van, we recommend Bilstein Heavy Duty shocks, which should last you a long time even under heavy workloads. The Monroe Gas Magnum is also a good choice if you want to save some money. If you have problems with the van sagging, look into an air suspension add on kit.
You can see all of the parts available for your van here:
2003 Ford E250 Van Shocks