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Install: B&M Vacuum Modulator for GM TH350 & TH400 Automatic Transmissions 20234YouTube Button

B&M Adjustable Modulator - GM TH350/TH400 Automatic Transmissions

GM TH350/TH400 Automatic Transmissions

PART# 20234

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$37.50   Suggested Retail
$30.38   Holleydays 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. For GM TH350 and TH400 automatic transmissions.


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


Emission Code5
FinishGold Iridited
Instructions IncludedYes
Product TypeAutomatic Transmission Modulator Valve
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

For GM TH350 and TH400 automatic transmissions. A minimum of 12" Hg engine vacuum is required for proper operation.


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       X  Holleydays 2020 20% off and DD
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