From the 1990 instruction manual:

Advanced, Competition Version of the RC10

Your new competition edition RC10 car is the latest state-of-the-art, 2WD off-road racer in the world. There is none better.

Our original RC10 car has won more IFMAR World Championships and ROAR Nationals combined than all the other 2WD off-road winning cars put together. It is by far the most popular 2WD off-road RACE car in the world. The READERS of RC CAR ACTION magazine voted the RC10 as CAR OF THE YEAR by a 6 to 1 margin over the 2nd place car! The racers know which car is best.

As great as the original RC10 is, we wanted something better, and we know you did to, so we've brought out the new RC10. At first glance it looks like a regular RC10. But it's much more than that. It has NEW, longer front A-arms with two NEW front shock towers which give more ideal shock mounting positions. NEW rear hub carriers with more toe-in for greater stability. NEW turnbuckles for easier adjustments. NEW idler gears which are strong enough even for monster trucks. NEW low profile front and rear wheels and tires, givin more steering in the front end and more traciton in the rear end. Which all adds up to give you the best 2WD car in the world.