Clive,
Welcome to the forum!!
I have a link in a post called "parts drawings" that has a supplier closer to you....csmnl.com
Just look down at the postings and you'll see it.
CMS is located in Lelystad, The Netherlands. If you click on that link, it will take you to the
Yamaha tractor info. You just have to enter the info about which tractor. Unsure about the
3600 hydro, but the 6800 takes good old 10W30 oil, I don't think they are much different.
Manuals can also be ordered thru www.yamahagenuineparts.com
Cheers
Rattosh51
YT6800