The tab washer is standard on various bits made by Brits. Most common on your SU throttle shafts. Most supply houses that sell carb rebuild kits should have the tab washers as well.
The funny looking lock nut is indeed a lock nut. The old style before nylocks were invented, the top of the nut is deformed to interfere with the threads on the bolt or stud it is mounted on. Good ole USA engineers did much the same thing by taking a perfectly normal nut and tapering one end then deforming it with a punch. Deformed lock nuts are still available at many auto parts stores.

Mike!

After calling numerous hardware store, autopart stores, tranny shops, performance (speed) shops, British car part companies, etc... I was beginning to get major headache. Decided to try some unconventional sources and looked in the yellow pages under aircraft part/ supply companies.

After 5th company, I hit jackpot. Flightcraft, located by Portland International, had what I was looking for; same size, same tabs, exact same as original, and only 85 cents each. It took around 45 phone calls total, but persistence paid off.

Hope this makes sense.... When replacing the o rings on pistons, there is a little metal piece called bridge (approx 2.5" L 1/2" W 1/4" D), which lies on top of each piston. 2 bolts are sticking up through holes on each bridge. There is a tab washer placed between bridge and nut.

It's easy to spot the assembly I'm describing. I pulled the silver OD unit off of red case, looked inside, and there it is on top. Those stupid washers are impossible to find, though I'm following up on some of the excellent suggestions posted; I'll find some sooner or later.