This is not increasing the torque exerted on the steering box, it is assisting with the effort of turning the steering column.
I am not so sure about that. The "fuse" in the stock steering system is the driver's arm and upper body strength. At a certain point, no matter how big the driver is, s/he's not going to be able to move the steering wheel. Think about a 14.50x20 tire that's stuck in a deep rut.
Now, imagine the torque generator installed inline on the column in that same instance. The generator now replaces the "fuse" of the operator's strength with a limitless (within reason) supply of torque. And the same truck with a tire stuck in the deep rut has a torque generator. Now, the operator turns the wheel and at some point, either stops turning the wheel or something breaks. Ever been inside the stock steering box? My bet is the box internals will fail.
Ok but I don't understand is why is eastern surplus selling these at $3000 dollars then if the steering box is know to be weak.....
Probably because their product, like all aftermarket products, are warranty exempt from "extreme use"-take your GT500 to the dragstrip, miss a gear and blow it up and see if they honor the warranty.
Also, if they're getting $3K.................. they're probably so thrilled that they're willing to comp a couple $50 steering boxes.
I recently drove a truck with m35-tom's power steering and if I had the money, I'd write a check yesterday. It's smooth, robust, powerful, replaces the worn out 50+ year old steering box, etc. The air assist kits are awful, they barely make a difference in comparison to "real" p/s and to me, they look vulnerable to damage in extreme offroading use.
I also think we should consider than in 1949 the REO engineers designed the steering box for what they imagined the largest tire would be-an 11:00X20 ND. I doubt they ever imagined something like the grippy radial 11:00's we're running, nor the ginomous 395, 14.50, 14:00 or 16:00 tires that are commonplace now.