WTB Catalytic Converter For 3.5" DownPipe

[twstdv6]

I am looking to see if anyone has a Catalytic Converter for a 3.5" DP. One that is not gutted out and can be fabbed up, or where I could buy one and maybe drop it in to bolt to the 4 bolt Y-Pipe if i give them the Measurements. also what is a good cat to use? Just wanted to check here first to see if someone had one lying around!