Actually, what happened was that Ford stopped funding all racing in the early 1970's, while Chrysler basically cut funding to only Petty. Junior Johnson shut down his team in 1971 because of no funds, and NASCAR would be much smaller if he hadn't, because he got the famous call from RJ Reynolds asking to sponsor his car for millions upon millions of dollars. Winston came in, showed all of these other outside companies like Perdue Chicken, for example, that racing was a great form of advertising that catered to the customer they had in mind. By the mid 70's the top teams had abandoned straight up manufacture support and had replaced the fickle car companies with somewhat more reliable consumer companies.