Nos,
Yeah, I did think a simple bit of hose poking out a hole had a hint of "emergency repair" about it..... Hole is round, I suspect had I noticed it before I got rid of the dead Yam the telltale fitting from it could have been used....
Marinautic,
Unfortuately at the moment I don't know the seirial No - I'll need to pull it out the garage to get some light behind the transom to be able to read it. (which I probably should have done before I fitted it......

) If it's any help, it's this livery:
http://cgi.ebay.com/ebaymotors/70,-7...027105008r7368 , complete with mis-matched front plate! If it helps narrow down the exact year it was a transom mount Automix (that inlet is capped and by the looks of it has been running premix for a while!

) and has no thermostat (from what I have figured out so far it uses a "cold idle" calibration). Manual tilt with "outside" assist rams & a webbing strap to stop it joining you in the boat!
I may be able to get to the serial no. tonight if that isn't enough.