Hawaiian Brokechanic

I just when through the same issue with my Silverado... I would check exhaust leaks at the flanges and to the muffler and repair to start. If no leaks, check down stream O2 sensors for excessive carbon and clean. If bad, replace. If P0420 persists, you may have a bigger issue with a bad lifter or a leaking exhaust manifold.

Did you get it figured out?

I noticed no one replied to your post... A bad temperature sensor can throw a DTC. It also could be a bad Catalytic Converter. I had P0420 and changed all my O2 sensors, plugs and wire and also exhaust manifold gaskets.... and the P0420 code still came back. Come to find out, my driver side cat was blown out! Here's a Video I put together:

Here's a quick video...ignore the reader promotion.

I have the AFE Differential Cover on mine...

Shoots Braddah! Sounds good! Maybe after we can catch some waves out at point panic!

Hello All, just a quick update... Just passed the 500 mile break in period and so far so good. I will tow my trailer (7000lbs) next week and I will update y'all on how the truck did with the new gears. I didn't smoke the tires yet and I may never...lol, but I did notice better gas mileage and acceleration. So I have attached a link to the YouTube video I put together documenting the install. DISCLAIMER: The video is not an instructional video that shows the step by step instructions. But feel free to ask me questions and I'll try to answer them I wasn't able to video me setting the gear patterns and pinion pre-load on both differentials, but rest assured I did set those to spec. If you're thinking of doing this yourself, be sure you have extra bearings just in case. This is a can do D.I.Y. project...just don't rush the install. With that said, good luck on your projects!

Final assembly was also challenging... It took me three tries to set the gear pattern to where it was acceptable. That step entailed assembling, disassembling carrier, pinion shaft and shimming. Pinion pre-load was also a pain, the yoke just didn't slip on. These steps were repeated for the front diff.

The issues I ran into was trying to install the races without damaging the carrier housing. I had Macgyver a race installer and this is what I came up with....and it worked!

Disassembling the rear diff was pretty straight forward. It was challenging by myself, but I got it done...

Yes I did....and it wasn't easy. I ran into a few obstacles with the install. I got the rear diff done over the weekend and worked on the front over the course of 2 days after I got off of work. I am putting a non-instructional video just highlight a few things. There are so many Youtube videos out there with step by step instructions, but they don't show and tell you the difficulties you'll encounter during the install. If you're not mechanically inclined, take it to a shop.

I've done all the work on my Silverado from the simple engine mods to the suspension lift. The gear swap is the largest project by far that I've undertaken. I'm like one of many true do it yourselfers that are on this forum... Knowledge is power and its saves me $$$. I will post picks here shortly. Just a quick note: Gear Swap is not so easy like these YouTube Videos make it out to be... If you are an experienced Mechanic or have ton's of life experience wrenching autos, then you'll know the work arounds. If you're like me, it's more on the (intermediate) life experience side of the spectrum. I don't have the latest and greatest gadgets to make the install easy, but I was able to get the disassembly done. I will put together a short YouTube video highlighting the project...

Check out this thread:

Nice! Looking forward to see more pics!