I looked on Disneyland.com and the only thing i was able to find was their disability guide book that you can download online
Disneyland Guidebook
It doesn't state anything about a GAC card or similar but i would inquire at guest services because at one time they had a Special Assistance Card(SAC) but i remember hearing that they may have stopped issuing them.
I wish i had a more definite answer but it can't hurt to ask when you get there or maybe someone might have a number to
DL's Guest Services and they could tell you over the phone?