You will need a 15/16" wrench for the blade side and a 7/8"
backup wrench for the outer pulley side of the deck. First jam
against the deck, the blade you are changing, with short length of
2" x 4", 2" x 6", or what ever else does the job. The blade nut is
a self jamming right hand threaded nut so it will require a wrench,
for the entire length of thread, to remove it. Once the blade
splines drop out of engagement with the shaft, you will need to use
a backup wrench on the pulley nut, to prevent the shaft from
turning. Remove the old blade and note the right side up
orientation. Reverse procedure for installation of new blade being
sure to install with the proper side up.
Hope this helps. I just changed mine yesterday and am going from
memory. However, I believe the wrench sizes are correct. If not,
adjust sizes where necessary as the procedure itself works
well.
Also, the mulching attachment I installed at the same time works
very well even though the attachment fit where it obfuscates the
discharge port is quite poor.