If you ever did find out it was a factory option, it would be a rare find. Also, if you want to haul a 1/2 ton of stuff and want to dump it instead of shoveling it, no problem. If you have a business that needs a dump truck, this ain't it. I'm assuming a dump kit was added to a
stock bed? I've seen those but not 1/2T. $5000 too much. Patina is another word for rusty surface metal and needs a paint job. The dump kits are about $1500 and add about 250 lbs. 12V electric/hydraulic, Includes: pump, cylinder, hardware. Peg's idea of a dump trailer is a good one. Then buy a stock 49 to pull it. You will then have a daily driver not a daily headache. Also there is no forum for 1/2T dumps, so you won't be able to post anymore
If some kind of honker heavy bed was put on and the added mechanism, better calculate the total load on the rear axle and frame as others have said. If it's a cobbed up Mad Max War Wagon, $1000.(including patina)
P.S. IMO: Motor not running is not a huge deal. The multitude of other problems that hides, is a big deal. Transmission, rear end, steering, brakes, suspension, Ujoints, gas tank, dump mechanism, wipers, gauges, heater, radiator, electrical, all bearings...none can be tested at speed/under load/under pressure, etc. $$$$$$$$$$$$$
