I don't think replacing them with same size threaded rod is the best plan ... I think dumping the wooden rails is the best plan.
Or as a compromise see if you can go up a size without compromising an old piece of wood.
I have done two boats with SS rails and feel way safer than relying on these rinky dink long bolts from 30 years ago ... if one broke ... i am pretty sure the rest are showing signs of pitting as the photo indicates.
for some reason I kept the four best ones removed from 505 four years ago ... they all are pitted. I didn't have a problem with the wood rails until I ended up with a 225+ plus crewman when he was trying to put a reef in off shore. and then subsequently the pins started to break on 526.
![[Linked Image]](https://j30.us/ubbthreads/ubbthreads.php/ubb/download/Number/1045/filename/J30%20handrail%20pins.jpg)