I have SM420's on the floor with both types of brakes. The 1/2 to 1-1/2 ton used an external band and the 2-ton and up used the dual shoe type with internal and external shoes.

52vff, your fire truck parking brake is on the back of the pump transfer case and could be made by any number of manufactures. My '57 has International Harvester parking brake parts, not GM.

I can't help with the SM465...

Mike B smile

Mike Boteler

1956 Chevy 3100 Resto Rod
1952 Willys M38 Army Jeep
1983 Jeep CJ7 Laredo
1984 Jeep CJ7
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Silver Spring, MD