My copy of the November, 1944 W/NG parts books is illegible for the fine numbers. On page 26 it gives the thickness dimension of the leather petrol tank washers (part #5060-42.
Steve or Ron, can you read yours?
Funny thing is that the number is a 1942 number, which makes sense in regards to substituting leather for rubber. The March 1944 parts book, however, still lists rubber mounts.
I haven't got the leather washer thickness to hand, but the parts book quotes 16 leather washers in place of 8 rubber..............and the upper rubber washers are thicker than the lower, plus one steel washer per bolt............
Regarding the latter, you do need to wire 'em tho as they do vibrate loose !! (trust me.... )
I've gone for the original rubbers on mine (still specified for contract C.11103).........far more reliable than rain-soaked, shrinking leather washers in our UK climate.......... (Don't fancy piercing my tank !!!)