Posted 9/10/2006 16:11 (#42790 - in reply to #42705) Subject: Re: "A" series
The newer 'A' series have a belt / chain spring tensioner that the straight 53's didn't have. They also have the split tops that fold open for easier access to the 'guts' of the row units.
I've always owned a 653A, but have heard my neighbor speak of the non-A series with distain for lack of the above improvements.