The Singer handcrank won't fit on a featherweight. Featherweights use a different motor and mounting position than the older Singers did. Featherweights don't have the boss on the back.
There is a guy selling handcrank kits made with the crank off aluminum windows but that's only a direct drive, not the 3 to 1 ratio a Singer handcrank has.
Here's the link.
http://www.ebay.com/itm/221-Singer-H...item2c9e77fc2f
Rodney