08 JKU rattle/grinding sound on acceleration (2k to 3k rpm)

Hey guys, my 08 JKU has been making this rattle/metallic grinding type noise while accelerating, mainly between 2k and 3k rpms. I had the catalytic converter replaced less than a month ago and the heat shield tack welds look good so I'm thinking that's not the issue. It drives fine except for this noise. Just wanted to see if anyone may have an idea of what the problem is or what to check.

My mods are:
3" Teraflex coil lift
1.25" Teraflex body lift
35x12.50r15 Goodyear MTRs
Have stock driveshafts front and rear, auto tranny




Any insight or suggestions would be appreciated. Thanks all.

Well whaddya know, on closer inspection it does appear to be heat shield related. Got under the jeep and saw this cat heat shield piece was rusted through and making contact so I bent it back a bit:



Which leads me to the next heat shield issue. The exhaust crossover heat shield is making contact with the tranny crossmember under load, especially in reverse. Here's a few pics of the jeep off and in park, notice how close the heat shield is:




Any ideas on how to remedy this? I'm thinking about wrapping some heat wrap around the crossover pipe to keep it from rattling against the crossmember but not sure how well it'll work. Suggestions appreciated.

Elmer, where does the sound seem to be coming from? I don't have very good headphones, so I cant make out the sound. However I have an 08JKU which has had a rattling noise coming from the rear, during acceleration, for years. I had it looked at once by the stealership, and they cited a problem in the spider gears. They fixed it, only to have it return a month later. I haven't experienced any noticeable performance issues, either. I hope that helps.