Yet Another "Metallic" Rattle Request for Help (Sorry)

Hi All, apologies to post another "Help I have a rattle" thread. It Has become unbearable, and embarrassing to drive...I know, I know.

Problem:
- Metallic Rattle Sound, like marbles in a tin can
- Started a while ago but thought it was something loose but it has gotten really bad over the past couple of months
- Sound Origin - mostly concentrated to under driver/driver side behind the engine, to left
- Only happens between 1000-2000 RPM while moving, can't reproduce while parked
- Only happens between 15-40 MPH
- Happens/occurs when accelerating
- Happens/occurs when "Coasting"
- Happens/occurs when decelerating - really noticeable
- Happens/occurs when turning, when turning right at low speeds or left
- At higher speeds can't tell because of the hum of the tires, it could be there it could not be there :shrug:

Truck Details:
2017 TRD OR Crew Cab Short Bed - Have owned since new
Miles: 60,025
Accutune OR Fox 2.5 Remote Ressy suspension
Devear Add A leaf full leaf spring swap
Upside down Mounts for Leaf Springs - forgot what it is called
Needle Bearing Mod
SCS Wheels
Widpeak A/T
Stoptech BB Kit all around
Icon UCA Delta Joint
Lowpro tonneau cover
Oil changed every 4,500 miles with Motul 8100 0w-20
All other fluids changed at 15,30, 45K with Amsoil or Liquid Moly (whatever I have on hand)
Brake fluid flushed every 10K with Motul High Temp Brake fluid

Video: [Coming Soon, waiting on go pro to arrive]
- sounds a lot like this clip from TXPATA24, but doesn't happen all the time like this video potentially conveys https://www.tacomaworld.com/threads/2019-tacoma-rattling-noise-1500-rpm.759090/

What I have Checked/Tried:
- Tried the usual take a mallet and knock around while vehicle is cold
- Made sure all heat shields are tight, bolts have surface rust but not rusted
- Made sure bolts are tight
- Took off skid plates to make sure they weren't loose or bent
- Made sure rear tire carrier lift mechanism was render in-op (spare tire/wheel is mounted in bed)
- Check play in U-Joints, Center Bearing
- Body Mount Inspection
- No wear in any joints, or torn boots, no oil leaks

What I have planned:
- have an appointment for regular maintenance with my independent, Danny (from this forum) but its not for another 2 weeks; but have to drive the truck because I am moving out of state and my other vehicles are over 5 hours away

Question:
- Can a Catalytic Converter make this sound at only a specific RPM/MPH and only when driving?
- IS there anything else I should be checking, thinking about?

Update:
[9/7/2025] - Bought bailing wire and hose clamps yesterday to test, but waiting on GoPro to show up so I can get a video of the noise and post it here before I test the hose clamps and / or bailing wire.

 

Check the heat shields around the cats. They tend to loosen up and rattle

 

Thanks, I have checked all of the heat shields around the cats, they are rock solid, was thinking about taking them off tomorrow to rule them out completely though.

 

They won’t feel loose to the touch unfortunately. You’ll need to wrap some baling wire around and make it super tight with some pliers to be 100% sure

 

Check the shields on the back of your disc brakes. If they are touching anything or even close, they will rattle. This was the problem for me. Took 2 minutes to fix, so it’s worth looking.

 

Take a rubber hammer and tap on the exhaust front to back, the brake dust shields Ect...

 

Good to note, will get some bailing wire and hose clamps today from the big box store. I have a safety wire fastening tool and safety wire, that might work to test the hypothesis but not sure if safety wire is strong enough, its just for securing bolts to my motorcycle with wire, hmmm...

Checked this because Danny when installing the brakes had to modify the front dust shield to fit the Big Brake kit. But I had the brakes done at 20K or 30K miles and never had a problem with them.

First thing I did, thanks for the thought and taking time to reply

 

I just wrapped baling wire on my passenger side 2nd cat a few years ago. Stopped the rattling and hasn’t been back. You don’t have to go overkill with it, it’s not holding any weight or pressure. Just to stop it from rattling

 

Good to know. I got bailing wire and hose clamps, to test, but I am waiting on the gopro. It was supposed to be here yesterday but got delayed. I want to get a video and post before I try the wire / clamps in case in the future someone else comes along and has the same problem I want them to be able to reference this thread. All of the other threads on the forum are "usually" the OP just asking the question and/or the video link is dead.