This should tell you everything you want to know! Lots of good stuff in the Tech Archives...
http://www.bigblockdart.com/techpages/abconv.shtml
Good Luck,
Jay
Installing a 4 speed in place of an automatic
This page has almost anything you'll want to know about Mopar 4 speeds. About 3/4 of the way down, it discusses the hump changes.
HTH
Jay