I think you are referring to the old GAC pass. As far as I know there isn't anything Autism specific. DD is on the spectrum. When we went last month, we obtained a
DAS - Disability Assistance Services from city hall. That is the new system implemented a few years ago. You go to city hall (with all the tickets for your party) with your child and tell them what accomodation they need. They tie the DAS to the persons ticket that needs the DAS. They will give you a return time for whatever ride you want. There are kiosks around the park where you can get additional times. You can also get one for DCA while you are in DL and vice versa. We found the system very easy and helpful.