Exhaust Nuts

Image Unavailable, Please Login Noticed a strange tick,tick sound at start-up. It stopped as the engine warmed up. Next cold start, I investigated and found an exhaust leak has started at the exhaust manifold on one of the cylinders. With new gaskets in hand and about to start the job, I noticed the new exhaust nuts are different then the ones that are on the engine. I ordered 114748 (on the right) but received 100115. The order says it supersedes the original and appears to be brass.
Does anyone have any insight to share?
It maybe me just over thinking this.