Hi, I've a reserve since april 25 until may 12, Ford Mustang Convertible or similar, but I only want Ford Mustang, not similar, can you assure me the Ford Mustang?, are there disponibility in these dates in airport or inanother office from Dallas?

Call the local agency directly for arrangements. Although, generally they don't guarantee a specific car (that's why they add the words "or similar"), a manager might be of help.

I suggest you call the office directly to talk to the manager about your concern. I do know that if that car isn't rented out prior to your arrival, they'd give it to you. My suggestion is to speak to the manager directly.