Out of curiosity I removed the lower and back trim of my deluxe other (passenger) seat.
Must confirm, no washers and also no retainer clip.
It's always possible that the 2 seats where once taken apart, however when seeing the actual result, much unlikely...
Concerning the remark that the washer(s) is in a dark grey fiber : I have the AMK seat moulding dlx kit (F-300) and there are 4 washers in grey/light black color.
So, is that then correct? They have an outside diam of 41mm (1 39/64 inch)...
Jeroen