how do i change this to an unused one?

[blackdiamond]

i have enabled the boarding seats with the wings on the banshee, and make them passenger seats. i have grunts, so i had to change to string id's too. but it says press X to board banshee. so i have been looking for a vehicle string id that is not used in my map. but i have the gravity throne and all. i looked for the pelican's press x to drive one, but i couldn't find it. i was going to change the boarding thing to the pelican's press X to drive hud message, but i just can't find it. any help on how to do this? i don't want to change the press X to board, otherwise it'll say that if i want to board the banshee for real