Box stock exists, but in that class, you can have fenders. The easiest class to jump into is BASX AM - its designed for new racers who want to give league racing a try. Its the simplest of cars, with no aero mods.
The Box Stock class does still exist & a cheaper route to go but you have to mess with the stock wheels & axles. The AM BASX class is a great place for the beginner to get a feel for league racing. No aero (fenders, wind deflectors) so an easy build with more time to work on your basic building skills & prep. This site is loaded with information to get you started & most everyone here is more than happy to help you out.
Hope to see you on the track soon, good luck!!!