Wonder if you have the wrong dist cap? I think the V6 4.3 will fit, but is wired differently inside the cap.
How would it be different? Power goes in the center, there's contacts at 60 degree intervals, and power goes out.
Because most V6's are not an even fire engine, and have split intervals of varying degrees of crank rotation on the crank rod journals. So a normal even firing distributor cap will not work correctly on an odd fire engine timing sequence.
