heres a another link. First one is for your area.
http://www.partnerstx.org/Resources/Autism/Support.htm

I had after many issues with my son. And a few dxs that were incorrect. It was a long road till the PDD one was put in place. Well 8 years .ALso LD one. Anyways a Dr who only did Autism that came and gave him a eval. Also spoke to me and I had to give a complete history of both sides of the family. He came many times. Then he Dxed him with PDD. Everything else had to be ruled out as you know.
Its a hard Dx to do I guess. Do not stop till you and his mom are satisfied. I still after 18 years of dealing with this feel like a noob lol
As its a ever changing issue with in them.
One Dr had Dxed him with something he did not have before this other Dr. That has come back up to haunt him so to speak. Thats why I said for you and your wife to be satisfied with the Dx if one happens. As you 2 know your son best.
Your son will do good he has the both of you ..
A side note I have to say these kids are so specail , they are such a gift from god as you know.