Mike,
Thanks for the additional photo; it is most informative.
The patent number stamped into the cover is nearly 2 million higher than the patent numbers stamped into the cover of the typical U.S.-made Houdaille '32 shock, which struck me as representing a big chunk of time. Patent number 3,613,842 was granted in 1971 to an individual in Chicago who applied for that patent in 1969 and according to the accompanying drawing is indeed for a hydraulic shock absorber of the type used by Ford (with a separate screw-on cover such as that on yours).
I was into '32s well before 1971 and I do not recall there being available a reproduction shock at that time, which of course proves nothing. Notwithstanding, they were evidently available and it would seem that you have four of them.
Sorry, as both of us were hoping for a different outcome. While perhaps not as valuable as an original shock, they sure look good and if they operate well they likely would be appealing to many hobbyists.