Ron,
You continue to be the King of great links! :)
Shelby did not get back to me yet. After reading the spec. I'm now better prepared with even more questions.
If I read and understand that correct my Class 4 coupler is suppose to be rated at 3 X the GVWR of the TT or in my case 30,000# in push or pull and not have the ball come out. While separation is not suppose to occur it does not mean the coupler is still usable at that rating. The key take away is the push and pull on the coupler appear to have the same rating. I will for sure ask that question to Shelby.
Also read the coupler must be capable of GVWR x 1.3 for vertical lift and or compression. Or 13,000# lift/compression. I take it my 3,500# rated tongue jack will not be a concern. And that the added force down on coupler into the tow ball from conventional WD should not be a problem either in the ranges the average RV'er uses a TT. That thought on heavy down pressure from WD crossed my mind as we have been going through all the coupler investigation.
Good find. Thanks for passing along.
John
PS, Yes it does seem the flat spot on the ball may be as simple as a good place to stamp the rating...