For what it's worth, I also have a pa-18 that used to have a 95 in it but was upgraded with a borer stc and currently has an 0-320. But no flaps. I did some digging, and to put them on, some Ia's tell you it's just a log book entry with the drawing, and some tell you it's a major alteration hence needing a 337. I looked up the type certificate data sheet, and depending on what serial no. yours is, there was two drawings for flap installation. I finally obtained the drawing I need for mine. Drawing no. 13766. Next for me, is to obtain the parts. If you need any more help, as far as getting the drawing you need, let me know. Good Luck.