Take the pulley/s off and go to your local mower repair shop.
One that fixes mowers not one with a massive showrooms & no workshop
If that is against your religion then take them off & measure them
Then go to an aftermarket parts suppliers web site and search for pulleys.
Ignore the bolt size or offset because hey are done with a bush that you can press out then replace with your old ones
Critical to match are the flange diameter & the drum diameter
The width is not so critical unless it is so different that the pulley will foul on the underside of the mower.