Carl. Gaskets will be easily obtainable from Draganfly, C&D Autos, Russells etc. But be aware that some after market gearbox gaskets are a lot thicker than the original paper gaskets, This will alter the shimming required for the shafts. I bought original type gaskets from Russells. You can google these firms for contact details. Ron
I always prefer to make gaskets myself. Then at least i,m sure they fit.
Some time ago I renewed both bronze bushes on the layshaft. I needed a thicker gasket to keep enough play on the shaft (!)