I have a POS 46" deck for my 1641 and is basically junk. It mowed like crap with standard blades on it and I bought a set of gator mulching blades with no improvement. Grass clumped up in the deck all the time. I wonder if that particular deck was designed for a rear bagger attachment.
Just didn't seem to have the a$$ to dischare the grass out the end. Maybe they need speed up pulleys on them to get the RPM's.