Slant6 Exhaust Manifold Brass Washer

Does anyone know the dimensions of the brass washers on a slant 6 exhaust manifold? I was sending my only one to a machine shop to have it made and the envelope was ripped open at the post office and the washer was lost. Lesson learned on mailing parts. I can’t seem to find them anywhere.
Just where does this "BRASS" washer go? I have some washers from when I replaced my manifold.
Donnie