The rear cover needs to go with the pto assembly. You will need to find out if it is a cast iron rear or aluminum rear in his machine. Or if you can find one for sale you can let his on the machine and not have to drain his hydro fluid.
Here is an aluminum rear cover.
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Here are the pulleys, cover, shaft and clutch
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The bearing assembly.
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Here is the drive shaft from the hydro output to the clutch.
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Pics are a help but go to the parts lookup and get a breakdown of the "433 rear pto" it shows everything needed. I don't see the manual for the 433 installation on here but maybe someone can post that up too. It has a list of everything too.