Willard A is made by Davis and takes a 20x1 needle. Millard is made by Standard and takes a 15x1 needle. This is accordance with ISMACS. You should be able to find parts for these on Ebay and other sites on the net. Yes the Davis shuttle and bobbin is longer. If you have no 20x1 you can cheat a 15x1 down a little until it picks up the bobbin thread. I do this my Davis and it will sew a great stitch and you will never know the difference.