If you wanted to waste time and money (a lot of people on this forum clearly enjoy doing so), you could buy a 10spd cassette, swap out the spacers for the ones from your old 9spd cassette, and adjust the set screw on your new mech to nullify your highest or lowest cog.
If you wanted to waste time and money (a lot of people on this forum clearly enjoy doing so), you could buy a 10spd cassette, swap out the spacers for the ones from your old 9spd cassette, and adjust the set screw on your new mech to nullify your highest or lowest cog.