R 10 P/U 2WD V8-379 6.2L DSL (1988)
5.
Punch a hole in the grommet with a pick, being careful not to puncture existing vacuum lines or wiring harnesses.
FIGURE 3
6.
Route the vacuum line under the dash to the glove box area. See Figure 3.
7.
Open the glove box and fold the compartment down to gain access to the rear of the dash. Locate the Max A/C line going to the plenum valve and
air recirculation door valve. The line is black plastic with an orange stripe.