Cold iowa winters. Engine heater help.

[woofy]

I'll start off by saying my 68 is in 100 gazillion pieces so this problem is not effecting me,very much. but it IS effecting my girlfriend and her 1970 c10(straight 6,3 on the tree) she loves her truck but its getting harder and harder to start it in the mornings as the day's get colder and colder. what would your advice be? battery warmer, freezer plug heater,engine blanket? sadly she has no garage to keep it in currently and its her only vehicle.

any help would be greatly appreciated and my apologies if this is posted in the wrong section.

for your viewing pleasure,on the back of my duramax the day we picked it up for her.