8-speed 8L90 shudder and harsh shiftingmajor
2016 is roughly when the 8-speed 8L90 arrived in the Silverado, and it brought a signature shudder — a shake you feel through the truck — plus harsh, clunky shifts. GM's fix was a transmission fluid flush with a revised fluid, which helps many trucks; mechanics also point to the older 6L80's high torque-converter failure rate. When the transmission or converter actually lets go, a rebuild or replacement is $4,000–$6,000. On a test drive, feel for shudder at light throttle around 25–45 mph and any lurch from a stop — a fluid service can mask early symptoms, so weight the maintenance records.
Sources: NHTSA complaint database, 2016 Silverado 1500 · Independent mechanic channel transcripts (3rd-gen Silverado; AFM/DFM lifter deep-dives)
a few hundred
Fluid flush with revised fluid
$4,000–$6,000
Torque converter / transmission rebuild