What type of fasteners are used to hold down the dash pad on 1964 Malibus?
The studs in the pad are pretty small compared to the holes.
If they are a specialty item, where can I get some?

On a 1965 the holes are pretty large as compared to the studs in the pad. The pad studs have nuts with washers, there are no other clips. I found that when it is installed the studs press more to the outside of the hole and not the center. The holes are larger to allow you some adjustment.
good luck.

Do you just use speed nuts?

My original dash pad used speed nuts.The replacement I got from OPG uses just standard threaded studs with regular nuts and washers.

Thanks Jim.
I will pick up some speed nuts.
My pad is the original with naughahyde stretched and glued over top.