Looks like some quality parts there. I have never seen one fail like that even when I was trying.
FWIW I didn't notice any performance difference going to Bosch plugs in my 5.7's.
98 Burb K25 4.10's 250K miles, new to me, pretty clean and stock.
95 Burb K25 3.73's CRASHED 250K miles, looks to have been rebuilt at least once, stock, bad rust, DE exhaust w/walker muffler, 8' western plow.
81 Buick Riviera GAVE AWAY with the infamous Olds 5.7 diesel possibly still going strong.
15 VW Golf wagon, TDI. Did the buyback on my 13 Jetta TDI wagon so it was basically a trade up.
96 Burb K25 3.42's SOLD at 340K miles, told it was all original, close race between engine wearing out or body completely rust out.