I also have a 1954 3600. I think this ( see photos ) is the part your looking for.
I have collected every single part for my brakes GM NOS, front & rear.
If you need any other photos of brake parts, just ask, I'll post them up to my brake parts album on photobucket.

I take photos of every part I buy.

If you look at the middle photo with the bluish background color.
I think ebay seller: washprotim , had them on sale about a month ago on ebay. You can search ebay by seller name. I don't recall if they sold on ebay.

see photobucket album, below:

http://s669.photobucket.com/user/glp0329/library/Brake%20Parts

George
in
New Jersey

1954 3600
A big help to many on the Bolt
Now cruising in
The Passing Lane