Don't buy the Dritz bobbins, the hole for the bobbin winder is too small and often the quality of these bobbins isn't very good. I only use vintage bobbins in my Singers 99,353,201 and 66 machines, several years ago I won an Ebay auction for 35 vintage class 66 bobbins; have plenty of bobbins for my machines now.
I've tried the newer repros and its just not as smooth.
Sharon W. in Texas