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Home >> GMC >> 1987 >> Forward Control 4.8 T, Standard >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Overhaul - THM 400 >> Testing >> Vacuum Modulator Check >> Sleeve Alignment Check
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Sleeve Alignment Check

Roll main body of modulator on flat surface and observe sleeve for concentricity to can. If sleeve is concentric and plunger is free, modulator is okay.