2500 exhaust Manifolds

I have a 2000 Silverado 2500 in my shop for a number of Codes....I believe the Exhaust Manifolds are leaking BAD. In 30 years of car repairs I have never seen anything like this. The manifolds are literally rotted off of the heads, some of the bolts are even missing or just rotted away, nothing else really show any signs of this but the manifolds flake apart like tree bark, yet the flanges and pipes are all solid. The owner has opted for a set of coated direct OEM replacement headers to replace them. Has anyone else seen this before.

this is more GM crap that led to their fall..
the bolts used are cheap low quality crap..the newer engines use a better bolt and much larger....

this is common with this year model...also when installing new crossover pipes be careful not to stress out these bolts..use the proper torque sequence and the correct thread material...holes in block will need to be cleaned out first..

we do these all of the time, more on fords though. Plow trucks are notorious for this.