I just picked one of these up, and can clarify a few of the items mentioned in this string.
Some of the trucks bodies (rear passenger compartment) are manufactured by a company out of Texas that uses prison labor to make assembly components. The same company makes license plates (no really), and other items with prison labor. Weather you agree with that or not, it is what it is. They might make some of the metal pieces that are formed and drilled for the body assembly. The company is called Unicor FPI. New stake bed trucks are sent to Unicor, then the bodies are installed into them per the FS specs, prior to filling an order via GSA for a specific customer (ranger district). Prison labor is not used outside of that one facet, hence the confusion about maintenance, etc. The truck will have a placard inside the cab with Unicor F.P.I, and whichever plant (Bastrop, TX is where the one we bought was made) affixed inside the driver door jamb with all the weights/capacities info.
Off road capabilities. The trucks are geared relatively low considering that they don't have a tow hitch to tow the 40k pounds (80k GCVWR) the transmission is rated for. It has a 5.29 rear ratio, and an auto transmission with 4.59:1 first gear (not including the torque converter multiplication). This makes them go near crawl speed. The ride is very truck like off road. The air seats and air suspension (in the rear only) help, but it is a very large and heavy truck. The leafs on the front are for a 10k pound weight load, so the ride in the cab is a bit worse than the ride in the back. Then again their are air seats in the cab, and fixed seats in the back, so this likely offsets. The one I have comes with an automatic locker (no spin) in the rear diff. I have not flexed the suspension to the point of one tire coming off the ground, so I cannot comment on that. I would think they should do fairly well in most situations save deep mud or sand. For that I think you would want 4WD, and more lugged tires (mud) or super singles (sand). I would not buy one to go rock crawling. The FS specs that they pass a 30 degree tilt table test. Basically the test truck is put on a big platform, hydraulically tilted to 30 degrees, and if it does not tip over it passes. The stock front tires are 38.5" tall, and the rear are 39.25" tall (measured with the tires at 105psi, so some tire deformation at the tread). You don't really feel washboards, but the jounce when you hit more pronounced holes/bumps will make full use of the air ride seats to the point of bottoming them out on occasion. I have to research to see if someone makes a dampening shock for the seats. A little compression/rebound shock, that is adjustable for the person's weight would be just the ticket, and settle things down when off road. If no one is doing that, I just gave anyone who is listening the next $1M idea. I'll be your first customer, and take one for each front seat. Fox, you listening? Approach angle is better than 45 degrees, departure is over 30 degrees, and break-over is likely the limitation due to tanks hanging aft the front wheels. The front axle hangs down, so likely only 9" of clearance...thought I have yet to measure. I would say that it should be near 4WD capable if comparing to an open diff 4WD truck of this size. If the 4WD has lockers, then it will never keep up.
Build quality. Everything on this thing is seriously over built. High HP/Torque version of the engine, High torque version of the transmission, oversize (for similar spec) auxiliaries (intercooler, fuel tanks, etc.), and the bolt on body is ridiculously overbuilt so as to survive a rollover. I have seen plenty of pics of rollover damage in my searches, and they all looked very intact. I did not find any that resulted in fatalities for the crew in the back, but that is not to say none have happened.
I am very new to the one we have, and it will sit in storage for a bit until we can clear out some of our other projects. The plan is to modify the body for use in a long time or full time use very heavy duty off grid RV. The body will be modified such that it has a side door entry, there is a pass-thru into the cab, and a rear platform that raises/lowers to the ground so as to hold a moto, 2x MTB, an oversize spare. We may or may not build a cabover sleep/storage area, which would entail raising the roof. A lot of cutting/welding/modifying is on the menu. If/when we get to that point, I'll start a build post.
Until then, if there are questions about the platform that I can answer I a happy to do so. As time goes on, I expect to learn/know a lot more about them so questions not answerable now may become known over time.
