I am in the process of purchasing a 1978 Mark V

Have the steering and suspension systems inspected a minimum of once a year at a tire and alignment shop, and any time you hear a clunk, rattle, or squeak. Ford has more trouble with those parts separating leading to loss of control and crashes than all other manufacturers combined. That started in the mid '70s when they figured out they could save millions of dollars a year by leaving four 5-cent grease fittings off each car. All replacement ball joints will have those grease fittings but knowing this history many mechanics didn't look for grease fittings when they did routine oil changes. To be safe owners had to specify that some parts had grease fittings on replacement parts. Later when it was well-known that most of the parts had been replaced on any car with 20,000 or 30,000 miles they would always check for those fittings.

The problems got even worse in the '80s with the Escort and Tempo. We call those "killer cars" because of how many came in on tow trucks with broken ball joints and outer tie rod ends. Dollars are more important than owner safety.