I'd sure like to get a find like that. I would say your Deere dealer (that's where I would go) would be your best bet for a manual, or try E-Bay.
If me, I would take up some of the slack with that adj. bolt, just so the chain wasn't tight.
I rent a 660 and like that size for my 4300, but would take the 550. Hope you got it for a good price.