OPEN STOCK FOUR WHEEL DRIVE RULES:
1. Trucks must have original factory frame, suspension and wheelbase. Must have original factory fenders, doors, box and floor. Must have factory fender wells and contain original factory glass and must have a full length dash and not cutting of interior structure allowed. Wheel wells may be trimmed to accommodate headers. Seat may be altered to a single racing seat. Must have stock front bumper. Any hood allowed with a 4 inch maximum hood scoop. (2010)
2. Engine must have factory cast iron heads and must be stock appearing. No aftermarket heads allowed. After market cast iron blocks are allowed. Block must retain factory cam height and bore spacing. (2011) Maximum 482 cubic inches. No V-10’s over 482 cubic inches. All carburetors must have 4150 style Holley base. Any single four-barrel, single plain or dual plain intakes allowed. No tunnel Rams, PRO Rams or sheet metal intakes allowed. Spacers may be allowed only to accommodate short deck intake or tall deck blocks on Chevys. A maximum of 1 inch carburetor spacer allowed. (2009)
3. There will be no electronic traction control that alters any engine functions. Factory sealed CD ignition boxes are allowed. Data acquisition is allowed, but there can be no connection to the ignition system.(2010)
4. Production fuel injection with aluminum intake produced by factory for that year and make of truck is allowed.
5. Trucks must have complete exhaust systems (headers or cast manifolds) with completely baffled mufflers that extend past rear of truck’s cab. No inner tube shielding. Maximum diameter will not exceed 3 inches. Cast exhaust must be reduced within 30 inches of manifold outlet. Fender well headers will be allowed with header tubing before collector being a maximum of 1 7/8 inch outer diameter. Maximum of two collectors and outlets per truck allowed.
6. One pair of traction bars extending forward from the rear axle horizontal with the frame will be allowed and must be bolted, not permanently attached to the frame and rear end. Rear suspension must have 5 or more factory style leaf springs that must be attached to factory perches in factory location. Suspension may be blocked with one removable vertically mounted block per side. (2007) Blocks must be directly above axle. When this block is removed the vehicle must be fully operational for pulling. (2008)
7. No front traction bar/devise allowed. Multiple shocks are allowed. Shocks must be mounted within six inches of the center of the front axle. (2010)
8. Fuel tank may be in stock location or relocated to inside of box. Fuel tanks and fuel lines in cab area must be metal.
9. Weights may be mounted to the front of the truck, but cannot exceed 60 inches from centerline of front axle. Weights must be secured during pull. No other equipment may be mounted on weight bar.
10. Hitch must be rigid in all directions at all times. A hitch angle of 0 to 30 degrees maximum is allowed with no leeway. This will be measured from hook point to hitch attachment point on the frame. Draw bar and adjustment supports to be mounted to frame only. Draw bar length, measured from center of rear axle to hook point, will be a minimum of 36% of truck wheelbase. Steel hitching device will be no more than 1 1/8 inch thick, no less than 3/4 inch thick. Hitch height not to exceed 26 inches. It must be a visible, clear hook mounted in horizontal alignment. All hitches will have only one adjustable supporting point and it must be located no more than 6 inches from hook point. That supporting point, if mounted to frame, must be as vertical at the rear most point of the frame if it is attached from above or below. If the attachment is to the rear end, it must be at or below the center point of the axle. (2007)
11. Engines may use after market battery operated ignitions (no magnetos).
12. Trucks must run one-ton drive train or less with one front axle, one rear axle, one transmission and one transfer case. All components must be stock appearing.