During the winter month does anybody run #1 diesel fuel or fuel additives? Ever had gelling problems?

No.1 diesel is kero and it contains more volitile distilates than No.2 diesel and should have a lower gel point.

How cold can it be to still be safe running #2 in a 6.2? I live in Montana and it gets well below freezing sometimes. If and when it gets that cold I probably won't be driving it, but it would be nice to know. What ratio should I run? 50/50?

You can run a diesel engine in any temperature. How do you think they built the Alaska pipeline.

Seriously if you take precautions like adding anti gel in very cold weather you will not have any problems. Most diesel dealers will sell winterized fuel in the colder months, this just means that they have added anti gelling agents.

If your worried about it take a sample of your fuel and put it in a clear container outside. If you see it gel than it's safe to say that the fuel in your tank has probably gelled also.