GM part# 89017825
The new gasket uses an aluminum shell (instead of plastic) with the sealing agent embossed into it. The older designs always had a problem with cracking around the coolant ports which allowed coolant to get past the sealing agent and creep into the lifter valley / oiling system.
Here are some examples of older designs:
This picture illustrates the previous two designs. There was yet another previous design not shown here. In the first design, no metal rings were located around the intake manifold bolt holes. What was happening most of the time was people were overtightening the intake manifold causing the plastic shell to crack. The top gasket in the last picture shows a later design where GM attempted to fix this problem by putting metal rings on the outer bolt holes. The last design (bottom gasket) had rings around all bolt holes plus the sealing agent and shell materials were upgraded to higher temperature materials. Appearantly GM discovered this wasn't enough so they redesigned the gasket to use an aluminum frame (latest design).
