Anyone know the difference between 65989-97A, 65989-97B, 65989-97C and 65989-97D? Thanks!

 

The last character in the sequence?

 

The difference is the post placement. Top post,side post, etc.

 

Do you know which post placement corresponds to which letter?

 

I doubt it is.. Usually when you get a sequence like that from HD, it means that the older part has been superseded or up dated (still compatible) with some improvement. So B is compatible with A, C is compatible with B, D is compatible with C. In the case of the batteries the terminals/placement and size are the same.