School me on Stock Eliminator?

They have gotten away from the VIN and fender tag info a long time ago. That is part of the concern, where too much aftermarket/non-stock/not exactly OEM stuff has been allowed over the years. But many of the older original cars are too rare and valuable to race so you will find many that actually started out a 6 cyl versions, including the SS/AH Hemi cars! Many ex-race cars have been converted back to their OEM configuration over the years also.