I bought this truck new and at 136k the cam and roller lifters started emitting a loud chirp at idle. After some online research this appears to be a frequent problem in this era Hemi. My local mechanic tore it apart and sure enough the rollers in the lifters were shot/wobbly. A new Cam and lifters were sourced but the Cam bearings are said to be not replaceable and "do not under any circumstance try and replace them". Does anyone have relevant experience with this?