Its a reinforcement bracket for the door mount spare tire carrier.

Peter Hewko

When I was in Fairbanks (-40 was rather common) and using my truck as a daily driver, I had a tank heater for the coolant (plumbed in to the block drain as mentioned previously), a 100w pad heater on the oil pan, and 75w pads on both the tranny and t-case. Even with this, arctic weight lube in every...