The battery was the same, but the connector was different. Requires cutting off the ends of the battery leads and the mower wiring harness, and installing a matching set in their place. If you didn’t need to have the option to remove the battery you could hardwire the battery to the mower. Or a down and dirty wire nut connection might work based on your particular skills and abilities. Definitely would have preferred receiving the correct part, but the need for modification justified a beer in the garage with some new tools.