Yes they are low shank, but the 328 is a zigzag machine where the others are straight stitch so will use a different walking foot than the others. I use this walking foot on my straight stitch machines. Works fine and inexpensive.
http://shop.sew-classic.com/Low-Shan...tch-P60400.htm
As far as a FM foot, this site sells several different types, it's personal preference or what the machine likes. I use a few different types. I even have one machine, a 15 clone, that I free motion with the straight stitch foot.
Cari