When Mopar was boycoting the nascar rule changes in the mid sixtys the Pettys went drag racing. The pettys wanted to race and nascar ruled the Cammer Ford and the Mopar Hemi out, May be Ford should have stayed home that year and the sohc may have been allowed back into the mix . Nascar's excuse was there lots of Chevy guys that want to see a winning car and the Rat engine couldn't cut it with out help.