[rotorwrench]

While the Mercury did share the same basic body shell starting in 1941 and continuing through 1948, There were differences in the trim and refinement that went into the body shell. If you have all the rods that support the headliner, they need to be compared to a ford of the same body type to be sure that they are the same. My guess would be that they are but that is only a guess. There may be differences of the rear quarter windows but I don't know that with any certainty either.

Headliners take some time to fabricate due to all the listings that have to be sewn into each panel where the rods support them. If a person had a headliner from a Ford to measure distance between the panels from front to rear then that could be compared to rod positions if the rods are still with the car.

A trimmer can make up one if they know the distances and the width/length. There are generally some card panels back there that finish out the transition from headliner to the package tray and door pillars as well. The rest would be the armrests and their associated finish cards. Material for the sun visors would also be needed.