Bought a 4Runner a few months ago for parts. Working on stripping down the engine to see if the heads were any good for me to use and this is what I found:
Cracked #4 piston:
Damage to cylinder head:
Also had a burnt valve on #2 as well as a blown head gasket:
This was an engine with 308K miles and it had absolutely nothing left to give! Was able to limp it to my house but that's it.