I believe my driver side cat is going bad. Sounds like internal rattling going on inside it, Any recommendations on replacement cats? and/or o2 sensors... Thank ya.

 

 

Magnaflow #99004M, #93689, or #94105 as stated above.

 

When I thought a cat was rattling in my truck it turned out to be a failed exhaust manifold-to-downpipe gasket. It would make a noise only when accelerating. An $8 gasket was an easy fix; much less expensive than a new catalytic converter. You might double check those gaskets in your truck before springing for a new cat.

 

I used a mechanics stethoscope and it is definitely coming from the middle of the driver side cat. As far as those magnaflows go, Do they require welding? I found a downpipe on amazon for about $290.00.

 

Often it is not just the downpipe gasket that is bad, the metal of the downpipe itself deteriorates at the welds on the upper part of the downpipe around the flange, which is what happened to mine. Complete Y pipes from magnaflow with cats are available, that's what I got, for around $450.