Robert M. Gary wrote:
Of course when I posted the first time I was asking about needing a 337
because it is not PMA'd. This post was asking if a 337 was necessary if
I could sign it since the work itself seems to fall under preventative
maintenance.

The need for a 337 and the fact that these lack a PMA (or other
authority) and hence may be unapproved parts are unrelated items.