[Harley Eaton]

There are two nipples on the brake booster valve ? Right? The large nipple is for the vacuum hose from the intake manifold (the vacuum supply). The smaller nipple is for the hose that goes to the vacuum modulator on the transmission.(no check valve here). The vacuum can near the battery is the reserve for the heater/AC. Larger nipple is for vacuum off the intake manifold. Should have vacuum check valve in the hose. Small nipple is for vacuum to the heater/AC. Hose goes through the firewall.