Any pics of Arrow Glass Muskie (or similar) stringers ????

[Wishiniwuzfishin]

I recently purchased this 1974 15' Arrow Glass Muskie Tri-Hull model. The previous owner replaced the plywood decking. I am getting ready to finish the interior and have been wondering about the shape of the stringers. It looks like he did a decent job with the decking but I can't help but wonder what the stringers are like. I sure hope he didn't just put in new plywood over rotten stringers. I thought I would drill a few test holes to check them but can't seem to find their location. I've tried a stud finder and even tried tapping to hear a difference but have had no luck with either. I thought for sure the stud finder would tell me but I'm not getting any consistent readings. I was wondering if anyone had any pics of the stringers in this model ArrowGlass or even any similar model. Also thought it would be a good idea if I knew where they were when I start to mount seats, console etc. Thanks for any help.