Thanks to everyone for their replies. The reason I brought this up is
that I am engaged in a discussion with someone on a Pipers discussion
group, and he is asserting that a PMAed part can be installed without
further approval or paperwork, whether or not the PMA was obtained as a
result of identicality, or as a result of an STC. My understanding that
was that STCed parts needed a 337 and an IA, and that the PMA had
nothing to do with it, other than meeting the requirements of 21.303
for offering parts for sale.