2021 lifter failure - post mortem

[RobZ]

I am up to 2 times lifter failures. 26000 miles(left bank) and now at 68000 miles (right bank). 

[Bryan Brooks]

I just bought a 2021 trailboss with 12,000 miles. the window sticker says 5.3 ecotec3 No autostop, How do i know if i have DFM? i am leaning towards that i dont have it because my build date was summer/fall of 2021 (i think, i need to double check), i just wasnt sure if there is a sure way to know?  also i found in my carfax report that i had to sign to purchase the truck (to varify that there were no recalls) that the lifters had been replaced at 8000miles (never mentioned by the salesperson either).... i guess thats good that they were replaced but i question if they failed or was it preventative?