The cars have not been "strictly stock" for years now. When we talk about cars racing up to speeds in excess of 190 mph, throwing several G's, how can anyone realistically expect stock parts to hold up. The rest of the car must be modified to keep up with those made to the power plant. The part most talked about when referring to 'stock' is the front end. Many of the body changes, again, are the direct result of managing speeds and improving safety.
Fuller: Which of the long time Cup models are FWD...Monte Carlo, Taurus, Charger or all.
Also, last time I checked, NASCAR is still wooing/persueding others, i.e. IRL/CART champ Tony Stewart as well as Paul Tracy, Max Papis and Boris Said to name a few to race their 'stock cars.
Actually, the reverse has happened from the statement made...open wheel circuits as well as F1 have recently been openly courting Cup drivers such as the aforementioned Stewart, Jeff Gordon and Kurt Busch