This is where you can find a field approval 337 that I did to approve lady legs already installed on my ‘52 170B when I bought it. Maybe this can be of some help to you?
http://www.cessna170.org/forums/members ... 0block.pdf
Lady Legs on an A model
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Re: Lady Legs on an A model
Thank you for the 337 link. That is exactly what my mechanic was looking for prior to learning that the Association’s STC is applicable to “lady legs.” I appreciate your willingness to share the work you had to put in to get your installation approved.
Erik
Erik