GM Service Manual Online
For 1990-2009 cars only

Harsh Shift D4 to D3, D2, or D1 for Chevrolet Chevy K Silverado - 4WD 1999

Harsh Shifts -- Fourth to Third, Second, or First

Checks

Cause

Spring Assembly (506)

Not functioning

Checkball

Plugged

Snap Ring (511)

Not seated