The headgasket blows and dumps a lot of coolant into the cylinder bores, oil passages, and eventually, the oil pan. Coolant makes a lousy lubricant, and as it gets circulated through the engine oiling system, it basically allows for metal-on-metal contact with the bearings and all oiled rotating or reciprocating pieces. That equates to a bunch of trashed bearing surfaces, lifter bores, cam lobes, you name it.
No doubt that they replaced the headgaskets, but the damage was probably done by the time they had.
1994 Super Coupe ('93 5.0L swap), 1990 Tbird 3.8L, 1982 Honda CB900F, 1972 F-100 SportCustom 4x4, 1970 Chevy Custom Camper / 20