Fitting rear shock on a targa

I am just finishing put a 750 targa together but they something funny about the washer that fix the stock on.
The wash are conceve (i have come across conceve wash before in agriculture) but they flat on all the parts listed .
Now the problem is the rubber on the stock is prouder then bush so a flat is no good and obviously the conceve washer has to go with the conceve facing out which to me is very strange.