My new NOS M151 jack arrived today. On the flat lifting surface is stamped "Capacity 1-1/2 tons". This means the little boy will safely lift 3000 pounds.
I intend to use it for off-road tire changes on my M1028, which has an empty curb weight of 5800 pounds, which equates to 1450 pounds per tire location, so the jack will be well within it's capacity. Instead of using the hand-crank rod for operating the jack, I plan to fabricate an adapter for my Milwaukee 18 volt cordless impact tool for quick operation. To fit the rectangular slot in the jack screw end, I will sacrifice a standard 1/2" x 4" socket extension and grind the male end to a rectangular male shape to fit the female slot on the jack. I will post photos of this if anyone is interested.
Hope this helps.