Today, while researching for replacement shocks for my Chrysler ambulance, I came across this video. It explains the difference between what originally came on our vehicles and the modern day replacement shocks. Finding the correct shock for your vehicle shouldn't be based on price alone, but more attention should be given to how that new part is going to work on your car. I would guess that most Commercial Chassis came from the factory with a heavy duty shock, however, all the replacement catalogs don't differentiate between a standard passenger car chassis and the commercial chassis. It will be up to the owner to seek out this information.
http://kyb.com/technical/monotube.php
http://kyb.com/technical/monotube.php