Hi. My 72 Ericson 32 has a Universal M3-20B engine. I regularly check the engine zinc and change it, mostly, yearly. It's located on the aft of the heat exchanger on the port side. In my engine manual there is a list of recommended spare parts. They list zincs as follows:ZINC 1/4NPT x 1-3/4 andZINC 3/8NPT x 1-1/4. The 1-3/4 fits the location on the heat exchanger. My tool box from the previous owner contains both size zincs. I've included a picture. I can not for the life of me find where the thicker, 3/8 x 1-1/4 zinc goes. I could find no reference to it in the engine manual except in the "spare parts list". Does anyone know if this engine has more than one zinc and where the shorter 3/8 zinc is located? Thanks