Hey guys, got the trans (722.369) rebuilt and installed. I started filling it with fluid when I noticed a leak. It was leaking from the Vacuum Modulator. When I installed the vac mod I did so with a thin o-ring. I have it out and looking at it, the O-ring is pretty thin. I downloaded the service manual and it called the part a "sealing ring" elsewhere
on other parts it'll say "o-ring". So, is the seal for the vac mod a rubber o-ring or a metalic sealing ring/washer like on the fluid lines?

Thanks,
Shawn