After listening several times, I conclude that the voice heard says:

"I'll never get these parts clean." One thing I feel 99% about is the word used is "these" and not "this".

It is obvious that Cindy believes her granddaughter's dead body had been in the trunk during the 31 days Caylee was missing prior to the 911 call. She tells George that Caylee is missing and KC had been looking for her. So, in this enhancement, it sounds as if George was as surprised as Cindy about Caylee being missing and the dead body odor in the trunk.

You can hear KC sniffling - not over the loss of her daughter - but because her parents were making her face facts.

I will never understand why the parents decided to help KC get away with murder.