B&M 20234 Adjustable Vacuum Transmission Modulator

For GM TH350/TH400 Automatic Transmissions

PART# 20234

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$36.15   Your Price
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The B&M® vacuum modulator is fully adjustable and allows you to fine-tune your shift points and shift feel. This is done by turning the adjustment screw inside of the vacuum line connection for more or less diaphragm preload, thus raising or lowering part throttle shift points and line pressures.


  • Allows you to Tailor Shift Points
  • New O-ring Helps Stop Leaks
  • Fully Adjustable
  • B&M Quality

Product Attributes

Brand B&M
Emission Code5
Manufacturer Part Number20234
Product TypeAutomatic Transmission Modulators
California Proposition 65 Chemical NameCadmium and cadmium compounds
California Proposition 65 RequiredYes
Part Number20234



This part is legal for sale or use on Emissions Controlled Vehicles, Uncontrolled (Non-Emissions Controlled) Vehicles, and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations.

Tech Resources

A minimum of 12 in. Hg engine vacuum is required for proper operation.


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    *Free Shipping & Handling only offered to the contiguous US on orders over $100, excludes clearance parts and oversized packages.

    Some parts are not legal for use in California or other states with similar regulations.