I've seen people convert 2WDs to 4WDs. Traxxas also makes a good example of a 2WD MT that can be converted to a 4WD. It may not be cost efficient or very reasonable to convert that Duratrax, but if he really wanted to spend the time and money to convert a 2WD F1 to a 4WD, someone could probably do it though it would have been simpler and probably cheaper in the long turn to simply purchase a 4WD Tamiya F201 F1.