Thanks all. The model is an M773LK 9KW genset. The part is a cast iron elbow
(part# 27-32003) above the back end. And yes, it had been "going bad" for a while. It was cracked it's entire length. Unfortunately, that side of the genset is right up against the hull
starboard side and I never saw any leakage or rust build up during routine maintenance
. It sounds like there might be an aftermarket stainless part available. Any help in locating one would be appreciated. This has been a shockingly (so to speak) expensive design/manufacturing flaw and failure. Evidently it's not unknown to happen and I wish NL had posted or sent warnings out.