I think what you are talking about is the
Torque Tube Retainer Sometimes for whatever reason one o-ring washer goes missing.
Or the two o-ring washers get stacked together inside the retainer cap.
My o-ring washer was missing.
You need one o-ring washer on each side of the rubber/cork seal/packing for it to seal correctly.
ilustration 1 Grp no. 5.576 washers Note: powerglide has same set-up shown, 37-54 all same size.
Parts Catalog part no. 595013
illustration 2 Chevrolet's 1938 Shop Manual
Where to find 
