Winston west series is sort of the step just under nascar
Same cars ,same rules , can race in the nascar events , but there not running the full nascar circuit.
http://www.southwesternstockcar.com/ww/wwnews_seriesinfo/ "The Cars: NASCAR Winston West Series cars are virtually the same as those raced in the NASCAR Winston Cup Series. They have a wheelbase of 110 inches and must maintain a minimum weight of 3,400 pounds. However, Winston West cars are powered by 358 cubic-inch V-8 engines with a maximum compression ratio of 9.5 to 1. Approved models include the Chevrolet Monte Carlo, the Pontiac Grand Prix, the Ford Thunderbird and the Ford Taurus"