I have four questions for this one.
1. What size belt drive belt will the John Deere 68 need?
2. How do I install it?
3. Where can I get it?
4. And is there possibly a manual for this mower anywhere?

Thanks. :)

John Deere parts online lists your drive belt as a part number M49920. This should either be stocked by your local JD dealer or they can order it. If you need assistance locating you local dealer use www.deere.com and dealer search.

This web site can also help you with the manuals.

Best regards, Alan