which pan should I use? I need to get height and length. I was thinking about using 9x13 and just carving it away. Or would a loaf pan be better?

Any advice would be welcome

I have used both. I use a 11 x 14 pan and cut it in half length ways and stack and carve for a big truck and use loaf pans for a smaller version (I have to say the loaf pans make it so much easier for a smaller cake - I use 3 of them) There is a little video that helps give an idea of where to start with loaf pans -
http://www.metacafe.com/watch/2940559/how_to_make_a_fire_truck_cake_fire_engine_birthday_cake/
Good Luck!!

I used a 12x18 and another 6x6 for the cab. I cut it length wise because I wanted it big. It was 6x18 truck. It ended up feeding about 40 people.

It needs to feed about 10 kids plus their parents.
I like jo_ann's idea (no offense FrostingKrista), I think that is more toward what I need.

Thanks to both for the help

yw, if you have any other questions, let me know. I actually wrote out the directions to this cake. (It's in my pics).