Hoo boy. There are TWO Delco systems, both with three individual coils (even think the coils are the same).
First was used on the GN and code "3" Bonnevilles through 87 (may have been some in 88 ). The module was for the early "single ring on the crank balancer" DIS. The module and the harness are keyed differently from the later "two rings on the balancer" version first used on the code "C" 3800 in 88 and is still used today. An "early" Delco module will not plug into a "late" harness or verse da vice.
In 1988-1991, the two ring sensor was used with a Magnavox ignition having a single coilpack with thre rectangular coils in a single unit.
From 1991 (Buick) on to today (Avis LeSabre I just had in NOLA has the same system) GM went back to the three individual coil Delco type. Since the same balancer and crank sensor is used, the Delco and Magnavox will plug into the same harness and either will work.
I consider the later Delco to have a hotter spark than the Magnavox (though the Magnavox can be upgraded with a Jacobs coil) and is better able to fire a .060" gap on a RapidFire #14. For the Magnavox I use a RapidFire #3 with .045" gap.
As gone into in great detail on my web page
, the Delco is a plug in replacement for the Magnavox provided you start with a complete unit (need the rectangular bottom bracket with three bolts sticking out of the bottom but not the engine bracket. This is what the coils screw to). from a yard de junque>
Have posted this before, maybe we need a FAQ.