I concur with Will.
I have examined the plastic gaskets in the pictures and from my car and the gaskets are only degraded where the coolant wicked in the channels.
I have a first design L36 GM gasket that was in a motor using Green phosphate coolant (not Dex) for at least 5 years and the gasket looks like new.
If only one car in 100,000 cars has the cooling system eaten away by acidic Drx then there is a problem with the produc
From what I have read you can not use Dex in a Diesel motor or it will void the warranty.
Time to try some G-05 at least it does not have 2EH like Dex.
Stock 96 Regal 3800 II