Free went out of business around 1940, National is a totally different company, but they also were is business long after 1900.
now there is a New National that was made by New Home before they got bought by Free.
All three companys had top clamp feet, but all three used a slightly different set. They also took different shuttles and different needles.
A picture would be real helpful to determine the Mfg of your machine. Most companies (other than Singer) sold machines under a host of different names.