http://www2.towerhobbies.com/cgi-bin...gt&FVPROFIL=++
Check out this link on Tower Hobbies above. It shows all of the options and specs and stuff. I don't own nor have I ever driven the RC10GT but I read great things about it and it's always suggested when someone asks for opinions on a great truck. I think it's single speed. As for gowing through tall grass - how tall? Thick, tall grass is a killer for any nitro truck.
Another option is something with larger tires - like the T-Maxx or the Sport Maxx by Traxxas. Both are very durable and go through tall grass a little easier. Sport Maxx is cheaper and two wheel drive. You can check those out on Tower Hobbies as well.
http://www2.towerhobbies.com/cgi-bin...AS&S2=&S3=&S4=
Maybe you should check out the associated web site or post another post asking people specifically about that truck.