here is info from pgatour site, do not see it on masters.org site..it is not clear whether they are using the within 10 shots rule as well as the low 44 with ties...
Note: In 1957, the 36-hole cut was instituted. The low 40 and ties and those within 10 strokes of the leader would qualify for the final 36 holes. In 1961, it was changed to the low 44 and ties.