The manifold rarely cracks, usually it warps with the heat and breaks the cap off the bolts. Most common on the passenger side rear (#8 cylinder). The worst case is a crack in the cylinder head, which requires head replacement.
One note: when mine warped and broke the bolt, I was able to easy-out the bolt after taking off the warped manifold. Found a replacement cheap, but hold on to your wallet when you find 1) the bolts cannot be re-used and 2) a replacement set costs about $150.
Otherwise it's a pretty easy DIY project. HTH
Yankee Clipper
2014 Winnebago Sightseer 33C on Ford F53 6.8l V10
2014 Honda CRV 4 down toad/Roadmaster Falcon2 with EvenBrake
TireMinder TPMS,Tiger, the Little Big Man minidachshund,
Rosey the minidachshund resident Princess-in-Chief