Blower page
Mine is a blower, rather than a plow, but you get the idea.
I had a similar parts shortage with mine, and ended up just tracking down salvage units to get parts from. it took years and cost money, but I got most of the stuff I needed.
It still needs about three hydraulic rams reworked (rusty piston surfaces) but apart from that...
I think your only option is to keep looking for a salvage unit. Even at 19k sales price that's a lot of truck - the engine would be worth that I think. It might pay to keep track of those auctioned too, in case someone buys one just for the engine and drivetrain and could let you have the parts you need.