Pro Stock (A Class) is allowed one diesel engine minimum of 470 cubic inches in size.
Pro Stock (B Class) is allowed one diesel engine up to 470 cubic inch. Weight classes are:
4600 kg, excluding driver
The maximum length of 13 feet from centre of rear wheel to forward most potion of tractor including removable ballast. The maximum width of tractor is to be 8 feet at the widest point including ballast. No four-wheel drive model tractors are eligible as a Pro-Stock entry. In order for a particular model of Tractor to be eligible as a Pro Stock entry there must have been 150 units produced of that model, it is up to the owner to provide documented proof should a protest be made.
Stock fuel for make and model of tractor must be used. Use of gasoline or alcohol is prohibited. Automatic transmission fluid may be used at a ratio of 400:1 or 2.5 ml per 1 litre of diesel fuel as an additive to prevent delivery valve or injector seizure.