I have mine from there and have had no issues for over 8000 miles so far, as far as the core, I got a set of 8 on ebay and just sent them in to pensacola as i ordered mine, if you are concerned with them as i was being that i didnt want to have to replace them again call them, I was confident that they were the ones rebuilding them and would stand behind the warranty, the guy there really knew his stuff