Factory timing settings for '96 4.3 V6 SX sterndrive

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The 4.3 V6 engine in my 1996 Campion 622 Explorer with Volvo SX sterndrive uses the shorter reach 15YC4 Champion spark plugs as opposed to the longer reach 12YC's. I'm confused on what the OEM manual requires for timing with shunt? Is my engine a GL, GS, or a GI? It's not a GI because it has a 4bbl Holley carb, and it has a steel stamped oil pan (not the *ribbed aluminum pan). I also burn 89AKI octane in it. One setting is for 6 degrees btdc (GL,GS*) one for 0 degrees tdc(GL,GS)??

 

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What is the factory timing setting for a 1996 Volvo 4.3 GS with stamped steel oil pan, short reach plugs (Champion RV15YC4) and running 89AKI octane? Is it 0 degrees TDC or 6 degrees BTDC??