Same thing happened to me.
I found an adapter set at Walmart for 15 bucks that had all the hardware to put a radio back in. Then went to a pick-n-pull and found a AM-FM radio for 10 bucks. 25 dollars and I was set again.
Just try the pick and pull plce. When they take the radios out they don't always take the bracket you need. That's how I got mine, was just laying on the floor.
Thanks for the tips. The stereo that got stolen was a Sony CD player and I used the factory braket on it. I was hoping to do the same on the replacement.