[rotorwrench]

The mid century Mercs didn't share much of anything in the parts & pieces with the Ford cars. They are somewhat similar but not the same. After 1952 the Fords & Mercs started to share a lot of stuff.

I've always been able to find good parts for the 49 thru 51 Mercury cars but they are getting harder to source for NOS stuff. As was already mentioned, a person can jack the front end off the floor and adjust the play out in the steering wheel centered position. If it's notchy in that position, it would likely only need a new worm gear on the end of the shaft. Sector rollers wear too but generally about half as fast as the worm gear. The Mercs steer really nice when they are restored to serviceable specs.