EVM1024 - Thank you so much! I should have mentioned that the reason I even brought this up, is because there is one very scary chainplate bolt replacement that was done prior to me purchasing
this boat. I knew going into the purchase
that this would need to be addressed ASAP. One of the shroud
bolts was replaced with a non-marine grade material that I suspect was picked up at Lowe's, right down the street... Why anyone would think this is a good idea, I cannot tell you.
My plan was to use an unused aft chainplate bolt (both aft chainplates were replaced with external's previously) to replace this rusting shroud
bolt. I removed one of the original aft bolts, and it looked remarkably clean without any indication of rust. Remarkable considering it is probably 47+ years old. However, my plan was shot down when I broke the rusting shroud bolt about three inches into the side of the hull.
I decided the best course of action is to replace altogether with an external plate. I should be picking up from a local machine shop later today. I will replace this one for now, and will likely replace the other five early next year. It will look weird with only one being external, but they should all eventually match and be "good as new."
After seeing the rear bolt in such good condition, I think the original chainplates themselves are probably fine, but I just don't like the idea of them being so old and me not being able to inspect them... I am very thankful for you sending Hans' information along. I went with his recommendations in regards to the size of replacement external chainplate.