What year is this canadian built Mercury OB

[grubber09]

I am thinking of buying this 850 Mercury O/B The serial number is 7091620

Could you please tell me what year it was built and if it was a good motor for Mercury. I have checked all the sites listed with model/year charts but they are for American built Mercs

Thanks,

 

[Laddies]

Re: What year is this canadian built Mercury OB

1977