I would not drive a 40 in snow/cold weather:
1) the morons out there do not realize what distance this truck needs to stop

even with disk brakes
NO different than any other truck
2) the heating is fine, but the defog is not
When maintained, they work just fine.
3) heating is mostly found towards the middle, some people claim their outside freezes off in the wintertime
the cabin can stay very toasty during some pretty cold times. Again, it is just making sure that your heating system is up to par and the truck is sealed well. If the heater core is plugged or there are a large number of air gaps in the truck, you will never be able to stay warm..
4) 40s need a loooong time to warm the engine up to optimal temperatures even in warm climates - if you live that far from work, you sure want a more comfortable vehicle
Mine warms up pretty fast the engine commonly warms up faster than the carb does due to an aftermarket header. A block heater can help when it is really cold, but the stock exhaust amnifold does a pretty good job of keeping things runnign well. Or, if you have a header, the coolant cycling plate works as well.
5) many 40s have been modified to have automatic lockers in the rear; not recommended to snow or ice
Bull, all it takes is a bit of thought and lockers are a non issue. I'll take the added traction any day..
6) rust, rust, rust
Everyone keeps complaining about rust. The 80 series will rust as well. A bit of preventative work would make a huge difference. Salting roads is hard on cars. The 40 is not inherently worse than anything else out there. It is just something that you have to deal with..
while it doesn't apply to me right now, if I were in the market for a larger, reliable, most capable vehicle in cold climates, I would sure look for an 80