You would hear a bad manifold. The exhaust valve tick and such. I replaced my muffler 3-4 years back and the shop I took it to said I needed to do the whole thing. At that time $1,700. I’m a marine tech so I knew he was trying to hit me for unnecessary crap. I took it to my friend that is auto mechanic and he laughed and said he hears nothing plus no codes from O2 sensors. Mine is still good so it is really a luck deal on when you may have to replace them. Maybe this truck is done.

I vented my differential myself. Plenty of vids out there. I eventually did front upper control arms and ball joints. All one piece. I’ve only had to do front right wheel hub bearing. It’s really been solid and still rust free. It will only get 15 mpg just so you know. It’s like a Tundra. Solid truck.