That sucks, big time! Ridiculous that GM ruined this things with the silly AFM...I am seeing lots of 2015ish units with miles on them for sale around here for around $15K (USD), kinda tempting, but then not really.
Mine is a 2006, last year of the GMT800, and last year of the 6.0L in the SUVs...The 3/4 ton trucks kept the 6.0L up until 2019ish, so clearly GM knew the durability of the AFM motors was questionable if they elected to keep the older motor in their HD stuff.