To only one shaft?
One on each side a total of four, and if using Durango, then should be 8, shouldn't it? two on each side...
Not causing problems, but measurements in the .277 or .184, etc are not standard in RC shims, they are always, .18, .20, .25, whole numbers.
I live in the US as well, and all shims sold in the US are in MM, not standard measurements. I also measured them and turned out to be .20mm for stock ARRMA shims. The same way you state "I am trying to help", you should make it clear about where are those shims, next thing you know someone is just putting 3 on one and leave one blank. Anyway, its unclear the explanation, then you provide a video that's too general.
You are referring to only the larger planetary gear inside the diff, you state three, so I guess its on one side of each of the three diffs. I don't want to do your "shim upgrade", its that your explanation is all over the place and nothing close to been clear.
Not causing problems, even the serial stock number you provided was incorrect.
http://www.nitrorcx.com/97c775parts.html
Under Nitro RCX there are all kinds of shims
http://www.nitrorcx.com/teenrcsppa.html
Select a platform on the top menu, and within each sub-menu of parts list, there will be all kinds of shims at a affordable price.