Chevy was tooling up there own version too when Nascar changed it's engine rule.
If they wouldn't have, they'd be racing 600 cubic inch motors with 4 cams or something by now.
I guess you could say the Hemi was too good and ruined the party for everyone.

As far as fwd bodystyles, there weren't any rear wheel drive cars being made anymore so what was Nascar supposed to do?

Only the nose is fiberglass. The body's are steel.