I recently removed the Shimano Square Taper bottom bracket from my Trek 950 Single Track with the idea I would overhaul and reinstall it.

While removing the unit I noticed the two rubber dust seals (or grommets) were different sizes. The side of the BB that had the smaller, ill fitting seal was dirty and that side of the spindle was pitted compared to the side that had the correct size seal.

I've owned the bike since new, and had never touched the BB prior to this. I have no idea how two sized seals could have been installed... just doesn't make sense.

Now, I want to reinstall the BB but can't find a replacement seal that is correctly sized (see measurements below), any ideas where I can find a replacement? I've checked numerous grommet/seal mfrs and no one seems to have something remotely close to the following sizes; any help is appreciated:

A-Bore: 16.3 mm
B-Groove Width: 4.5mm
C-Groove Dia: 18.3mm
D-OD: 21mm
E-Thickness: 5mm