Are they compatible? What are their actual specs?
I want to say absolutely not, however I can't find my drawings of the classic shank. The pre-64 has a tenon .740" long with a diameter of 1" and 16 pitch threads. This is most likely the same on both but the pre-64 has a coned breech whereas I don't believe the classic does.
I could be wrong...........wouldn't be the first time . Somebody smarter than me will come along shortly with the answer.
You are right. Post 2009 they switched to 1 1/16th x 28 tpi. I know this for certain. Barrel tennon was cut to 1.020 (I believe)