If you are in the city, go to any Cap-It or truck outfitting store and get the grill inserts. Everyone has them and they do an all-right job.
If you are out in the boonies where your truck idles all day or you really want your truck to be warm in this arctic cold snap, then look at rigging up a belly tarp and a quilted front grill cover. Heavy-duty truck shops can recommend a tarp maker. Check with International Truck for recommendations.
These trucks like to be warm so if you can minimize the -45deg air coming in, your truck will be happier.
And Princess Auto has oilpan heaters, as does Cambodian Tire. They're all basically the same. Temro is a supplier with a warehouse in Edmonton -- check them out online. You might also look at battery blankets (you'll need 2) to keep the batts from freezing up if you guys dip lower than -40. Park with your back end into the wind -- that helps too.