Assuming its this one? And you mean the bed knife screwdriver tool as well...how do I know which screws to get?
I can't check the number at the moment, but the best way to do it is search for your mower in the drop down menus near the top of the R&R website... Toro > GM1000 > then select the parts diagram for your mower's model number (found on the serial number plate on the frame). They will list all the options for your mower, including the screws. It probably wouldn't be a bad idea to have one of these
to help break the old screws loose. You attach the Toro bedknife screw socket to it and strike it with a hammer to break them loose.
When it comes time to reassemble, be sure and follow the torque specification/sequence in the factory service manual. I think
it calls for anti-seize on the screws, but it has been a while since I read it.