I didn't feel like paying $10 shipping for a $2 part ('04 washer) so here's what I did to space out my countershaft sprocket for O-ring chain use. My local Ace Hardware had the hardened 7/8" and
8mm washers. The 8mm washer probably isn't necessary but, obviously, doesn't hurt. I used a bit of blue Loctite on the bolt and torqued it to 23 ft/lbs.