Copper Compression Washers

Good Evening All,
I am currently restoring a Mk-1 2.4 litre engine. The bolts for the cover at the bottom of the sump had copper compression washers which were parts # FW.105/E. According to SNG Barrat these were 5/16 inner diameter, 2mm thick and are easily available. On my car’s original engine these washers were sandwiched between two additional washers of the same size that were however much thinner. Does anyone know who stocks these? Help here is greatly appreciated. Thanks, Chris

Are you sure they are original, and not somebody’s attempt to stop a leak?
Maybe the studs have too much unthreaded shank?