The Thrifty web site lists the number for the MCO location as (877) 283-0898. The address listed is 9302 Airport Blvd, which is the terminal, so that has been updated. I would guess the phone number is probably the current number, too.
I have rented from Thrifty several times at MCO (not since they moved into the terminal), and I've always been very pleased with the service and the condition and cleanliness of the cars.
I've never been very picky about exact make and model of my rental car, as long as it's in good condition and big enough to fit me. But the Thrifty agents will certainly try to get you a particular make and model, if they have it available, and if it's in the car class you reserved. Just ask politely and see what they can do; be sure to ask BEFORE they start running through the rental procedures, so they won't have to reverse a bunch of stuff at the last minute.