Make sure you get a FACTORY service manual, versus an aftermarket version (Chiltons, etc.). The aftermarket manuals are better than nothing, but not nearly complete enough to repair most systems. Watch that you get a '71 or newer manual, since there was a fairly significant change in wiring and some mechanical designs (differential, transmission, etc.) in early to mid 1970.
There are usually a couple of factory service manuals on ebay. Note, do NOT get an Owners Manual, which is just the little booklet that you get when you buy the car. And don't be afraid of ebay, its a GREAT source of used and NOS (New Old Stock) Opel parts. Do a search for "Opel"under
www.ebaymotors.com (or just copy and past this url to your address bar):
http://motors.search-desc.ebay.com/O...trypageZsearch
HTH
ps. Where in Canada are you at?