Seawater pump failure

I recently had a failure of the seawater pump on a Sea Ray 310DA with 350 Mag engines. The entire pulley shaft and bearing moved out of the pump impeller housing a couple of inches, until the belt came off, and the engine began to overheat. I planned to have the pump rebuilt as a spare, and when talking to the parts supplier was told that these pumps have been unavailable for several months, and that Mercruiser was redesigning the pump. I believe the older version of this pump had an internal snap ring, but this pump does not. It appears that the only thing holding the shaft into the pump housing is the front seal. Has anyone else experienced this failure, or know anything about Mercruiser redesigning this pump. I have twin engines, and I assume that the pump just installed is still of the old design, so I potentially have two large repair bills coming my way if these pumps fail.

Issue resolved to my satisfaction with Mercruiser.