There must be something wrong in the description as a YT624 is 24" wide and an HS828 is 28" wide. It probably fits HS624 and HS724 as well (this might be what they meant). I read somewhere that the auger housing extensions for the older YS624 will fit the newer YT624. The same might be true for older YS828 housing extensions fitting YS928J and YS1028J. Just a thought....