11/16" drill bit
Try ENCO
http://www.use-enco.com/CGI/INSRHM
I'm surprised you don't have a local industrial supply store of some sort. Avoid the home centers for drill bits if they really matter. I'd rather spend $20 for a good HSS bit than have a cheap one break in an oil passage (been there, done that).
Also, 11/16" is a pretty oddball size for a twist drill.