Rattling when I let off the throttle?

[stopcomplaining]

My truck is a 2000 exploder sport 4.0 OHV with manual tranny, 115,000 miles. When I am in third or fourth and I let off the gas, I can hear a loud rattling sound. It is only noticable with the windows down. It sounds like maybe a caliper rattling against a disc, but it happens when I'm not on the brakes. I've tried sticking my head out the window and it sounds like it's maybe coming from around the oil pan or tranny area? Can't be sure.

Is there anything I should be checking? Thanks!

edit: I forgot to mention, there is a little bit of a rubbing noise coming from the tranny boot while in neutral.

 

[Buffalosports]

I had (have) the same problem. Over time it will happen when you are both on the gas and directly as you come off. Check you cat. coverter heat shield. My welds broke. I let it hang for awhile until I could actually see it hanging. Then I took out a hammer and slammed it off. First the top just lifted off and then the bottom I took off. I am still getting a slight rattle from something on the exhaust. Not sure what but I know it is from the exhaust because it rattles when I am on the gas. As the engine goes up in rms it gets louder.