1996 was the year when GM/Merc changed from the Gen II engines to the Gen+ (yes, as well as a Gen II drive, the V6 engines also came in Gen II. Confusing if you're new to these parts
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Having said '4.3LX', I'm thinking it's a Gen II engine with a 4bbl Weber 9600 series carb. If you want to verify that, the Gen II engines have 12 intake manifold bolts, in at 45 degrees, the Gen+ engines have 8 intake bolts in vertically (or you can post the engine serial number and we can look it up and check for you).
Chris......
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EDIT: Just checked, a 1996 2 bbl Gen+ V6 was also called '4.3LX'.