Doc, the DF if .275 thick whereas the 911 is .250. Other than that I can't help you out. You MIGHT be able to put the kydex in boiling water and then (With gloves on, it's gonna be hot) mold the sheath to the blade by hand (around the blade/grip junction. I would try and find some way to put the blade in a flat press so you would get a good molding on that(oh and don't forget to use at least a couple thicknesses of masking tape on the blade.