Issue fixed! Just thought I'd post this update since it seems like a lot of people were having the same problem....
When I replaced my rear-left axle, I put in an aftermarket one... Everything was fine for about a week, until the clunking started.
Lesson learned, DO NOT buy aftermarket axles. I found out I had an extra set of OEM axles that I put in the storage over a year ago. I put the OEM axle in and now the issue has been resolved. No more clunking or any noise for that matter.
Funny how a used OEM axle is more durable than a brand new aftermarket one.
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