If your 763 is 1999 or new (serial #512250001 or above), there is compartment behind the seat built into to ROPS for holding the Operator's manual. Look there, it may still be in there. A lot of owners didn't know it was there because it is hidden by the seat.
If no Op manual, you can purchase it in CD form or paper from Bobcat dealer. The CD is less expansive. Someone on Ebay usually has manuals for sale as well.
Engine oil is 10-30W GC or better (change interval @ 250 hrs.) Hydaulic fluid calls for Bobcat Hydrostatic/hydraulic fluid (change interval - filters 500 hrs. & fluid 1000 hrs). I'm sure you will get other posts here about other fluids to use. If you do not use the Bobcat fluid, use only ISO 46AW and be prepared for some additional Hydrostatic whine out of pumps & motors.