Noise while auto shifts.

I just heard it today so I have not really checked anything yet. I was on the highway when I started passing someone off and it seemed like at the top of one gear going to another right at the last moment of the shift there is a vibrating sound coming from right in front and underneath. My exhaust is tightly welded and my Jeep almost tries to clunk when it upshifts after the initial downshift to gain acceleration. The sound is kinda light like it would be the exhaust but it's very tight. I could not find anything like this with the search. I'll be working on it today but I figured to check if anyone had similar problems.

Check the flex plate bolts. Also, I know you said your exhaust is tight, but check the cat converter for a lose heat shield.