There were two engines available. The 429 cubic inch was for the Talladega/Yarborough model and the 351 cubic inch for the Yarborough Cyclone Spoiler II. These were made because NASCAR had a rule that for any car raced they had to have at least 500 cars available to the public for sale. The Yarborough Cyclone II wasn't very popular and was discontinued after the first year. They are now one of the most desired collectable automobiles today. Originally selling for around $3800.00 in 1968, a correct model today can fetch as high as $100,000+ with everything original and with Cale Yarborough's signature, according to Barrett-Jackson Car Auctioners.
Source: Wikipedia > Cale Yarborough
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