Noisy on drive
Record whether noise appears under positive torque and changes immediately when load is removed.
REAR AXLE · NOISE · DIAGNOSIS
Rear-Axle Noise: Identify the Operating Condition First
GM separates rear-axle noise by when it occurs. “Rear end whine” is not enough to pick a bearing or gear.
APPLICATION: 1993–2002 Firebird / Formula / Trans Am with rear-drive-axle noise. Modified housings/gears require their manufacturer setup specs.
Noisy on coast
A coast-only pattern is a different diagnostic branch from noise that follows vehicle speed regardless of load.
Noisy on turns
Turn-sensitive noise directs attention differently than straight-line gear whine and should be separated before disassembly.
DO NOT BUY GEARS FROM SOUND ALONE
Inspect fluid, leaks, loose fasteners, wheel bearings, tires and driveshaft before concluding the ring-and-pinion is the source.
FPV RULE
OBSERVE → MEASURE → ISOLATE → PROVE → REPAIR → VERIFY. Do not turn a symptom, DTC or catalog fitment label into a parts order.