You want 75/90 GL in all the gear boxes/rear ends. Steering too, or the equivellant. You can do that before you get here. I run it year round. Make it a point to seal up the air leaks - a pencil sized hole will cancel your heaters. Rocket tape is good around the windlows, etc. Naturally, you wnt good weather stripping. A couple of 750 watt freeze plug heaters will start it. I would not recommed anything but a can of starting fluid. Otherwise you get too much at a time, while starting. I believe in lots of heat to start it. Push the clutch in while cranking it - that minimizes the drag & it will spin faster. -60 is rare & you best be very prepared with all the cold gear, for safety. When that cold traveling, I always carry a 20# propane bottle, weed burner torch. You should have the alcahol snifter bottle on you compressor. in the "Old Days", the driver got one too. Ice in the air system is the most likely thing that will shut you down. Always carry some Power Service, or the equilivant pour point depressant, for you fuel, but otherwise, be sure that you have #1 fuel in your system.
I always think the -20 F is perfect traveling weather. Good traction on ice/hard pack. NDT tires are notoriously dangerous in those conditions and contrary to some Folks opinion, it renders the Duce and other vehicles with that tread, Vulnerable! So be careful. In general, those conditions can be dangerous. One should always use care! I've been here almost 40 years and, and... I think it was along in 1970 that I got my M37. It was many years, that it was my daily driver, along with a couple of M211's for the heavy stuff.
Lee in Alaska