Tractors must be naturally aspirated. No turbos or blowers - except Oliver 99GM, etc. Gas, diesel or LP fuels only. No alcohol or nitrous oxide fuels may be used in tractors. Gas is allowed a maximum of 750 specific gravity.
All tractors are subject to random fuel checks.
Rpm's allowed will be determined by the Nebraska test chart. Any tractor not listed will use manufacturer's data. All tractors to have positive throttle stops. Tractors must have the stock engine, frames, transmission, rear end and axle housings or manufacturer's replacement. Stockheads and their replacements are to remain unchanged in outside appearance.