Look for markings that start with RP, otherwise it's probably an aftermarket knock-off...good luck finding out what it is if it has no markings... Here's an example: https://www.ebay.com/itm/NOS-GM-Del...026663&hash=item58e9c848fc:g:mMcAAOSwnHZYSuVd
The eBay stat is '70. Marks you see are from assembly process. I'm quite sure it is nos It's not mine