hon30critter,
Would the ACF hitch have replaced the jacks and chains in the late 1950's? Yes and no (depending on RR). Older TOFC RR's were slow to change their own equipment to the ACF hitch. Newer TOFC RR's were quicker to change over because they had fewer cars or were buying new ones with the ACF hitch already installed. Also, the older RR's sometimes were betting on some technology that became dead ends, like the NH's Clejan cars (also used on the NKP, IIRC). The NH's Clejan cars were built in 1956, IIRC, and they ran for several years on the NH (and they never got AF hitches). So, it's safe to say that the late 1950's would have seen several kinds of trailer tie-downs running at the same time or even on the same train. It took until the 1960's for the ACF hitch to completely replace all other kinds of tie downs. For example, the NH did not convert to ACF hitches until the arrival of it's fleet of G-85 flats in the mid-1960's.
That screw jack that you showed ( http://www.walthers.com/exec/productinfo/229-7102 ) is exactly like the ones used on the NH's own TOFC fleet from 1937 until the 1960's. They used a pair of these, fore and aft, on each trailer with a wooden beam (4x4 or 6x6?) laid across the tops of them. The beam was perpendicular to the trailer. It's lack of stability was more than made up for by the 4 tie down chains with tightening hardware.
The tie down method shown in the NKP link shows a completely different kind of tie down compared to the CGW & NH method. Note the spring loaded chains and permanently mounted jack stands as well as the custom chain tie downs to the rub rails, which seem to have tracks on them. The CGW & NH method had solid, unsprung chains mounted to eyebolts in the floor located towards the center of the car while the jack stands were moveable and individual.
I have some NH pics at home showing what they did. I'll have to upload them later if I can remember to do so. The CGW & NH-type tie downs are, IMHO, an easier thing to model due to the lack of special hardware required.
Paul A. Cutler III