Sorry for the cross-post with the mechanic's forum, I have an old Kestrel 500 frameset which is missing the hanger/boss for the braze-on front derailleur. Because this frame lacks a seat tube, the hanger bolts onto a flat tab jutting from from the down tube. Also, the bolt holes in the frame are offset, rather than in a straight vertical line.

Does anyone know where I can purchase a replacement? I've searched online but have only found the rear derailleur hanger. I will contact Kestrel, but their website provides only a physical mailing address. Thanks in advance!