Fisher 30 Refit: #76 (revised) A Nipple That Fits -NO MURIATIC ACID !!

This replaces the previous #76... which contained a glaring and dangerous error. Do not .. repeat Do Not use muriatic acid in place of "barnacle buster". You want diluted Phosphoric Acid.. approx. 5% concentration .
On Sunday, we discovered that a common American threat 1-1/4" pipe nipple ( NPT) would fit our exhaust mixer elbow.
We will be sure to use a good thread sealing technique. MDI Marine in Vancouver Washington ( not BC) who made this nice Stainless replacement for the Yanmar GM exhaust mixer elbow, supplied some copper anti-sieze compound. Thanks ! They are great folks to do business with. I ordered by phone on Thursday afternoon and the part was waiting in the mailbox on Saturday !
After sleeping on this overnight.. I think it wise to use either a bronze or stainless, rather than common steel, to prevent electrolysis from eating up this nipple.
I apologize for previously suggesting Muriatic Acid. Please do not use it.