KEEPING ICE OUT OF LOCKS
The design of the door-lock on the 1980s Ford is such that they are an easy target for ice, snow, and freezing rain to plug them, making it impossible to get the key in the lock.
For years, I have simply smeared a healthy dab of plain old Vaseline over the key-hole, pushing some into the key-hole as well.
Vaseline is an excellent water repellent and does not seem to be affected by winter temperatures of 20-below or so, other than to thicken considerably.
The only draw-backs are a continual streak of sticky goo down the side of the door (this is easily washed away), should the temperature get summerlike for a couple of days, and forgetting it is there and getting it all over your Sunday-go-to-meeting clothes.
Another method :
Just a few minutes ago, I was making some preparations in advance of a snow forecast.
I was fixing to do the Vaseline trick and had an epiphany; there were several of those page-sized magnetic advertisement signs (the ones businesses hand out to stick on the refrigerator-door that have emergency numbers and such printed on them, along with a bunch of advertisements) stuck to the clothes-dryer, awaiting some useful purpose.
I plastered one of these over each key-hole, thus preventing the invasion of any ice.
While neater and cleaner than the Vaseline trick, the Vaseline has one advantage in that it remains in action while driving along in an ice storm, whereas the sheet-magnet needs be removed when driving, else it would most likely blow away.