You might want to keep checking on Kijiji and your local dealer. I've seen a few used cab for sale in the past. Also, you might want to contact the Ottawa dealer B T Macfarlane, they sell many F series every year and might have a line on a used cab.
I didn't have a cab on mine for the first winter blowing snow, I was never quick enough on the rotator to prevent snow blowing back at me, and that got old very quickly.... packed snow between you and the seat!
The snow is has all melted away in Ottawa and it looks like we're headed for a mild winter. ... Back to cabs, you can't go wrong with the Curtis cab if you find a used one or decide to take the plunge on a new one. I installed my own and the job was relatively simple.
Good luck with your search and all the best for the New Year...
Well I didn't fit mine, it came with the machine but as far as I know it is a standard accessory because I see a lot around my part of the world with the same style of thing.
In my case I have a one piece counter weight on the rear of the machine and there is two bolt holes running vertically about a hand span spacing. It has a shaped steel plate about 1/2" thick bolted through the two holes. It overhangs the counter weight and has a tow ball attached to it.
If you can't buy it as a part, it shouldn't be too hard to get it knocked up locally if you don't have the gear to cut and drill it.
Hope it helps..