Borrowed this picture from another brewer and it does a great job of showing the difference.
Part number for impeller magnet assembly is 0809-0107-0200

They also recommend changing the thrust washer part number for it is 0809-0043-1000
Cost of the impeller runs between 24.00 to 27.00 plus shipping and the washer is .069
I don't have a problem with priming with my set up but some that I read says it does improve priming.
God Bless
Dominus Vobiscum
Swagman