stock engine requirements: Chevrolet 350, Chrysler 360, Ford 351 engines. Must be all-steel except intake manifold. Engine maximum displacement of . Engines typically cannot be modified except for aftermarket carburetor, intake manifold and exhaust manifold. Many different tracks and sanctioning bodies have variations on these rules of what constitutes an open late model, limited late model and a late model stock. Crate late models Crate late models use Chevrolet small-block engine engines that have been sealed with a special tag. Typical motors include the GM 602 and GM 604 engines. Recently the GM CT525 crate has been a popular choice of racers and some after-market Ford motors have surfaced in competition. Crate engines are sealed at the intake manifold, cylinder head, front cover, and oil pan with special twist off bolts. Crate engines must not be altered, modified, or changed in any way from factory specifications. Crate late models have three primarily Southern region touring series: the Durrence Layne Dirt Late Model Series, the United Crate Racing Alliance and the Fastrak Crate Late Model Series. Popular late model racing series World of Outlaws Late Model Series Lucas Oil Late Model Dirt Series Southern All Star Racing Series (SAS) Southern Nationals/Spring Nationals International Motor Contest Association (IMCA) United Crate Racing Alliance (UCRA) United Midwestern Promoters (UMP) Mid America Racing Series (MARS) Midwest Late Model Racing Association (MLRA) United Late Model Association (ULMA) There are hundreds of additional unsanctioned regional and national special events run throughout the year. Major annual late model events Bama Brawl - AL: third weekend in February Ice Bowl - AL: first weekend after the new year Wild West Shootout - AZ: mid-January week plus of racing Winter Nationals - FL: week-long 2 tracks Tampa and Daytona leading to the Daytona 500) King of the Commonwealth - VA: early April Show-Me 100 - MO: Memorial Day weekend $100,000 Dream - OH: richest race of the year Firecracker 100 - PA: Prior to July 4 weekend Silver Dollar Nationals - NE: late July Prairie Dirt Classic - IL: last week July USA 100 - VA: not to be confused with the USA Nationals same weekend USA Nationals - WI: $50,000 3rd richest World 100 North/South 100 - KY: $50,000 week after USA Nationals Topless 100 - AR: $40,000 3rd week in Aug HillBilly 100 - WV $25,000 richest one day race World 100 - OH: most prestigious race Knoxville