Great question bro...........I have no idea lol!!
I grew 4 females, all were pretty similar..........Large yielding, great structure, crazy trich coverage and all had some kinda lemon/lime flav/taste............2 were louder in smell than the others.
I never grew the original Mountain Jam so I don't really have anything to comapare it too.
I know that wasn't very helpful bro...sorry about that, just trying to be honest..........There are more threads on another web site that has a lot more info/details on how do identify the "Jack" traits........Might find it useful my friend.
Goodluck with the grow........Feel free to post any pics/info ya want :)
Cheers,
Danny