Fantasma: Wikipedia says:

The McGovern-Fraser Commission established open procedures and affirmative action guidelines for selecting delegates. In addition the commission made it so that all delegate selection procedures were required to be open; party leaders could no longer handpick the convention delegates in secret.

But you said:

The party hacks & old timers (ie the corrupt bosses, et al) immediately got together post-convention and changed the rules, effectively locking the progressive wing of the Democratic party out in the wilderness in perpetuity.

So you seem to be saying that the McGovern-Fraser changes were undone, or subverted by later changes. Those later changes are the ones I want to learn more about. That Wikipedia article doesn't help. (Sorry, I haven't had time to read all the articles about McGovern-Fraser.)

The reason I ask is that I had the impression the McGovern-Fraser changes were still in effect. At least I believe they are here in Minnesota. Maybe it varies on a state-by-state basis.