After looking for these mufflers for over a year I found several vendors offering mufflers that claimed to meet Gabriel's specifications. I ordered a pair and received one from Mexico (OEM Gabriel) and one from China. The Mexican, unlike the Chinese, which do not have grooves, has the correct locking ring grooves along the shock absorber tube. I contacted customer service and asked for a refund (which was flawless) and asked me to get another replacement from Mexico. When the replacement came…