Just want to make sure I know what I am talking about...

[87GNSteve]

When converting to vacuum brakes it is best to use the brake booster from the NA G body Regal, Monte etc. that had Dual diaphragm and not the single diaphragm booster from the Malibu or El Camino cars. Correct?

 

[Red Regal T]

Well, that's what G-body Regals, Cutlasses, Grand Prixs and Bonnevilles, came with .... dual diaphram. However, most Montes I see have the single diaphram. They must work just as well, although I have only handled or used the dual diaphram myself.