GM 6L80 and 8L90 torque converters use phenolic-style thrust washers between the damper hub and piston that have a high failure rate, melting and distorting due to high localized heat.
These two new upgraded thrust washers from #Sonnax are made from PTFE-impregnated bimetal material for improved durability:
Fits 4.3L 6L80 & 6.2L 8L90 units with RPO code M5U: https://www.sonnax.com/parts/6158
Fits 4.3L & 5.3L 8L90 units with RPO code M5U: https://www.sonnax.com/parts/6159
