How are the vacuum lines attached on a stock 1972 Chevy Cheyenne three quarter ton 350 small block turbo trans?

The vacuum lines on a stock 1972 Chevy Cheyenne 3/4 ton with a 350 small block and Turbo Hydra-Matic (TH350) transmission are attached using a combination of clamps, fittings, and sometimes push-on connections. There's no single definitive diagram as routing might vary slightly depending on options (like air conditioning) and any modifications done over the years. However, the general connections are as follows:

* Transmission Vacuum Modulator: This is the most important vacuum line. It connects directly to the transmission's vacuum modulator. This modulator controls shift firmness and timing. The line usually runs from a port on the intake manifold (often a dedicated port labeled "Trans") to the modulator. The connection is typically a small hose clamp.

* Power Brake Booster: A large vacuum line runs from the intake manifold to the power brake booster. This provides vacuum for power assisted braking. This connection uses a larger hose clamp.

* Distributor Vacuum Advance: A smaller vacuum line usually runs from a port on the intake manifold to the distributor for the vacuum advance mechanism. This helps adjust ignition timing. It generally uses a small hose clamp.

* Other Potential Connections: Depending on options, you might have other vacuum lines for:

* Air Conditioning: If equipped, the A/C system will have several vacuum lines related to the operation of the HVAC components.

* Climate Control: Vacuum might be used for controlling vents and airflow.

* Emission Control: Some emissions systems used vacuum lines. (1972 was a transition year for emissions, so this might or might not be present)

Finding the Connections:

The best way to determine the exact routing is to:

1. Consult a Factory Service Manual: A factory service manual for your specific year and model Chevy Cheyenne will have a detailed vacuum diagram. This is the most reliable source.

2. Examine Your Truck: Carefully trace the lines from the intake manifold to see where they go. Take pictures as you go. Be cautious not to break any brittle lines.

3. Use a Vacuum Diagram Online: While not as reliable as a factory manual, you can find some generic diagrams online for 1972 Chevy small block engines with TH350 transmissions. Use these with caution and verify against your truck.

Important Note: Vacuum lines are often brittle and prone to cracking with age. If you're working on the system, it's advisable to replace any suspect lines. Use appropriately sized hose clamps to ensure a secure and leak-free connection.