For purposes of
section 5410 of this title, paragraph (1) of subsection (a) shall not apply to any person who establishes that he did not have reason to know in the exercise of due care that such manufactured home is not in conformity with applicable Federal manufactured home construction and safety standards, or to any person who, prior to such first purchase, holds a certificate issued by the manufacturer or importer of such manufactured home to the effect that such manufactured home conforms to all applicable Federal manufactured home construction and safety standards, unless such person knows that such manufactured home does not so conform.