Hello there Dorn,
Here is a link to where I ordered my crank seals, they are 5mm in width instead of 3.8mm and the picture that is used on the web site is wrong but the top choise ( Grey Nitrile Seal ) is the ones I have they are correct width for the gear side of the crank and I'm pretty sure they will also work on the mag. side as well. less than $3 and I think with some care the seal can actually be worked down 1-2mm's in width because the outer frame of the seal is wider than the sealing area itself, I have been planning to do that myself on a piece of coarse sandpaper taped down on a flat piece of glass.
Anyway here is the link. best wishes. and remember the seal in the pic on this site is wrong but the seal is correct.
http://www.motionindustries.com/motion3/jsp/mii/productSearch.jsp
Peace, Map