Keith;
Yes, I have an early 10 gauge Lefever side pivot with rod cocking which does not have the stop screw or block. The extractor on that one will not however simply fall out. You have to actually spring the stem a bit to remove it, was made that way intentionally. This was though close to 10 years prior to the H grade being introduced.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra