After some serious googling, I still came empty handed. (I don't have access to such a machine, but I need this piece of info to make sure an installer script will run on one.)
I did the same serious Googling to reveal this article.
According to the article, Mountain Lion would have a bash version
3.2.53 unless there were more updates after that. Bear in mind that Mountain Lion was already on limited support phase.
Also you can read the message Apple sent out on its mailing list about the same update.
From OS X 10.5 to present the bash version is 3.2.XX. The revisions vary.