Hey everyone, I started my truck today to head home and soon noticed a grinding knocking at a certain rpm located (seemingly) by the rear of the engine. I noticed it will do it in drive or if I rev it in nuetral. drove all the way home , then sat for a while messing with the rpms. Seems to happen at 1900 or seldomly at idle. then suddenly, it started to fade away again!!! Any help would be greatly appreciated!

 

Exhaust bumping on something??

 

after checking it out today, I learned thats what it was. Got worried over nothing lol, not a trans, engine, or suspension issue as I feared. Thanks!