Welcome to the forum!

I'd take a good look behind the front bumper, you should have one. the 5.0 is e85 compatible and one should have been installed as standard equipment.

if, for some reason, you do not have one, i would go to the ford dealer to get a factory unit. you would be hard pressed to find one of better quality in the aftermarket.

back when i sold parts we sold "Kat's" brand heaters, and they were very good, but i from what i can tell the factory units are quite a bit better.

good luck.....
-50 ... brrrr.
i've gone to work in -29, and that was cold enough .... -50 -- yowza!!!!