It's nice to fire off all those well known names but I checked all of those sites and they do not have them for 1966 K10. They have 1969 and up hubs. If you have specific knowledge, post the part number. This is how bad info gets into print. Summit has the same one I linked. "Selectro Mile Marker" and they are $15 more than Michigan Truckspring. (again, the one I already linked). If Summit has free ship, it's about a wash. I did not find any other locking hub. Let us know.
A comment from a parts supplier, just for reference: "The wheel hub used on GM 1/2 ton 4x4s with Dana 44 closed knuckle front axles has a unique internal spline length so the common aftermarket lockout hubs that fit GM open knuckle axles will not fit the GM closed knuckle axles."
No reason a smallish snow plow will not work. The power is probably there. A manufactured plow will state what vehicles can handle it. Home made: different story.
What motor do you have in it?
See post #5:
http://67-72chevytrucks.com/vboard/showthread.php?p=7064136