Exhaust diameter at cat to Y-pipe flange

The flange on my y-pipe is rusted off and I was going to cut the other flange off and put in a flex pipe. What size is the pipe on both sides of that flange? Looks like 2 1/2 but I wanted to check before ordering the flex pipe.

Thanks!

I believe the stock diameter on the y is
2 1/4. Someone correct me if I'm worng.