I've heard some dealers who think that putting a service body on a 1/2-ton truck to keep the cost down is quite acceptable, and even preferred. There are even body companies who are foolish enough to help them out by doing it. Here is the main issues I have with this scenario:
Just for example, let's take a Chevrolet 1500 long bed.
GVWR: This is the most the truck can weigh legally with everything including passengers, cargo, fuel, etc. The GVWR for this truck is 6400 lbs.
TARE: The empty or shipping weight of this vehicle as a pickup truck is 4592 lbs for the base model and 4893 lbs for the LT model. We will be super conservative here and use the base model.
The math: 6400 lbs GVWR minus 4592 lbs empty weight equals 1808 potential cargo capacity.
Now, as a half-ton truck 1808 lbs cargo capacity less passengers, fuel fuel load, etc is just fine and actually quite a lot, but when we add a steel service body which weighs on average about 1,000 lbs, then add a 300 lbs ladder rack, there isn't much left. But, let's be fair. I'm going to remove the pickup box and credit the cargo capacity by about 300 lbs, so now as an empty chassis, we have 2108 lbs available.
Now take the body with rack of 1300 lbs and deduct it from the available capacity of 2108 lbs and this now leaves us with a maximum payload including passengers, full fuel load and cargo of only 808 lbs. Let's put two people in the cab at an average of 150 lbs each and about 120 lbs for fuel fuel tank. This now leaves us with only 388 lbs of available cargo capacity. This is a ridiculously small amount of capacity. On the 3/4-ton it would be a minimum of 1500 lbs and often more.
But. . . that's not the real problem. Some people might say, "we can't control what people put into a service body, so 388 lbs is a lot." I say, that you CAN control what people put on their truck that they buy from you.
Here's the real problem. How many closets do you have in your house that are empty? I ask this question in every training session and I never get even a single one. What do we do with closets? We fill them up with stuff. Do we ever empty them? Only when we move. If we had more closets, would we have empty ones? Not a chance. It seems to be human nature to fill up those empty spaces. Well, that is a service body. It is a bunch of closets on a truck and people who buy service bodies do exactly the same thing we do at home with our closets. They fill them up. Except they fill them up with heavy things like tools, and machines, chains, etc. And. . . they never empty them. If there is empty space, they fill it. Then they put some more in the cargo bed area too. 388 lbs would go by so quickly, you wouldn't even notice it happened.
But that's not all--not by a longshot. Let's look at safety. Half ton trucks have half ton type tires and are meant to only carry half ton type loads. They have half ton brakes which are designed to stop only half ton loads. They have half ton axles which are designed to support only half ton loads. They have half ton suspensions which are designed to support only half ton loads. In fact, everything about the half ton is half ton rated. A steel service body is not half ton rated.
Even an aluminum service body on a half ton is still not a very good idea, although it is about 40% lighter. A fiberglass body is even lighter, even as light as 500 lbs plus the rack, but the primary thing to remember is how people use service bodies versus how they use a pickup truck. All those closets means only one thing: they can fill them up with stuff and they don't get emptied, so it is loaded 100 percent of the time. Pickups are not.
As a dealer, all of this puts a dealer in the liability loop in a big way. Suppose one buys this truck and gets into an accident. Not an on purpose, but an accident. Suppose someone got hurt. Suppose there are lawyers getting involved. Suppose they start checking the facts. It would be child's play to find out that this body should never have been put on this truck. Guess what comes next. Cha-ching!
Worse than this is someone is seriously injured because an axle broke under the load. I've seen it happen on trucks many times--even on trucks we sold and that is why I learned this lesson the hard way many, many years ago.
My best advice is to steer clear of half ton trucks with service bodies of any kind.