My experiance with plastic parts on engines is pretty much if they are there they will break, warp, distort, leak or some combination of above.
If they have not failed yet, they will.
And usually when you don't want them to (who would want them to) and when you try to remove a replacement from a pick a part yard.
They exist because as long as a warentee can be maintained, and they are respectfully cheap to manufacture and last the lenght of a warrentee the will be used.
Those of us dedicated or stupid enough to hang on to car because of some emotional attachement to a chunk of iron and problems both enjoy the benefits of the hobby and achieve the benefits of some really crappy parts.
This guy is needed to keep some of this stuff running affordable, him and others like him. 'Specially now that a GM bean counter has determined that the buying public did not want a badge engineered product that was cheaper to make and improved the profit if only the damned thing had sold but the profit picture can be improved by dropping the line, closing the factory and putting people out of work.
Buyer Beware
Be screwed
and be damned.
I'm gonna have to book mark this thing, I may need one some day.