The "brake booster" is the motive power for vacuum assisted "power brakes". Power disc brakes were stock as base equipment on a 71 C30. Power steering was optional though.
* VIN/Model Decoders
* Power Team Charts (engine/transmission/gear ratio)
* Post Your Pickup SPID Blazer SPID Suburban/Panel SPID
* RTFM ... Read The Factory Manuals... download 'em here