Just stumbled on this thread, Hayduke. I've owned a few Ford 7.3L's and also live at altitude where it gets cold as balls.
Plug your truck in when you can and makes sure your batteries, glow plugs and glow plug relay are functioning well. If you can't, a mechanic can test them in less than 30 minutes at most. Regarding additives, I use Howe's Diesel Treatment in every tank, available at most auto parts stores. My truck starts after sitting idle for days in a yurt outside of Stanley--consistently the country's "low". I swear by the stuff and it's supposedly alcohol free, so you don't have to worry about drying out your seals.
"All God does is watch us and kill us when we get boring. We must never, ever be boring."
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