Generally
The copper sealing washer, the location is under the nuts that hold the diff block. This is a newly manufactured washer in almost exact original design. Cadillac spare part number is 1456254. The copper washer's dimensions are Internal 10.1mm. External 17.9mm and the thickness is 1.5mm, so a perfect washer both in terms of dimensions, appearance and function for an original renovation. It takes 12 washers for 1 car.
