[HO455]

Originally Posted by jabborabbo

Is that practice still common? The reason I ask is due to my impression that the shooters in the back of the truck look “modern” (like within the last 10 years at max) both in how they’re dressed and the firearms they’re using….

I don't believe it's as common as it once was due to the complexity of modern engines. That being said turbo diesel trucks would lend themselves to this kind of modification.
As I recall this modification was usually only done on used trucks. So instead of trading the old truck in on the new one it got a second life in the fields.