Was the car on an incline when you noticed the leak?

I would locate where the antifreeze is dripping and visually follow the trail until you locate the source.

I have had antifreeze leaks which made its way down the car frame.

A tail pipe repair should not cause an antifreeze leak.

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles