You can make one yourself. First you will need an airbox off a TBI Cadillac motor.
Donor cars to look for:
^^Some of these have the Northstar and it won't have this air box if it does.^^
You will need everything pictured, including the mounting stud.
Your existing b-body air box is held down with two studs. Remove them from the TB and separate the two pieces. Reinstall the bottom bolts. Now, screw in your new offset stud from the Cadillac
Once you have that you are going to need a length of PVC pipe for it. It should be 3" in diameter. You can get this from Home Depot. You also need a 45 degree elbow. You will have to put a hole in the side of the air box for the intake air temp sensor (passenger side). You will also need to install a small breather filter into the valve cover where the hose comes out and goes to the original air box.
It should look something like this.
It adds a great throttle sound and may help performance a bit.