Does the Emission label not show your vacuum routing? My ST's are not here right now for me to look at.
edit: Ahhh, here you go.........
Item Part Number Description
1 18A318 Vacuum control motor—panel/defrost door
2 18A478 Panel/defrost door (full vacuum position)
3 — Defrost airflow
4 — Side window demister airflow
5 18B545 Temperature blend door (full heat position)
6 19860 A/C evaporator core
7 19A813 Recirculation air duct door (full vacuum position)
8 — Outside air inlet
9 18A318 Vacuum control motor—air inlet door
10 — Recirculated air inlet
11 19805 Blower motor
12 19A566 Vacuum reservoir tank
13 — Vacuum from the engine intake manifold
14 19B888 Function selector switch
15 18495 Heater control valve
16 18476 Heater core
17 18A559 Panel/floor door (full vacuum position)
18 — Floor airflow
19 18A318 Vacuum control motor—panel/floor door
20 — Panel airflow
NOTE: The two vacuum lines to the vacuum reservoir tank are not interchangeable. NOTE: The A/C vacuum check valve is internal to the vacuum reservoir tank and cannot be serviced separately. ( The check valve should be in the side that Line 13 attaches to. )