To give you an answer, it would be helpful to understand what information you are really looking for.
For example, the high failure rate items are not really "high". The cars all came with a great warrantee and with rare exception, they all drove right through that period without a failure.
There are really two considerations in my mind when addressing parts sparing.
first is what parts are relatively easy to find now but may be hard to find in the future.
Second is what parts are shared with a very large number of other GM vehicles and will be easy to find for many years to come.