The Military coil retro-fit is not a bolt-on deal; the spark plug connection is in the wrong place. People here seem to work round that in various ways and they report that it works well.
The ignition system used in your Challenger is called Bendix Scintilla; use that when you search here for posts. There are a lot of posts on this subject.
BTW….The SEARCH field on the home page here does not work…..but the other SEARCH field on the “Active Members Forum” page works quite well. Try those keywords there.
Here’s a seller on ebay with the Military coils; there are a lot more selling them:
https://www.ebay.com/itm/232218550107
And here’s one thread here that shows pictures of what is involved:
https://www.aomci.org/forums/topic/mercury-kg7-parts/
It’s an interesting job that you’re in for…..
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