I came across these 2 sites looking for an old Evinrude snowmobile service manual. They both have lots of vintage manuals, all of the ones I looked at are factory manuals. A lot of the manuals go back to the early 70's and some go back to the mid to late 60's.


Vintagesnow.com (There is a link for the master manual for 85-95 Polaris models here too.):
http://www.vintagesnow.com/

Vintagesleds.com
Home link:
http://www.vintagesleds.com/index.php
Manuals link:
http://www.vintagesleds.com/library/manuals.php

vintagesnow.com also has a link for various motors used in the early days.
Both sites have other resources for carbs, clutches, etc, etc, etc, on these old beasts.