Regarding rear main seal- put a little grease on crank journal and then put the plate with seal back on and torque it down. Take it back off and see if the seal is making contact with the crank journal. If not, then you need to remove metal evenly off the metal seal holder. I have seen as much as .040" needed to be removed in order for the seal to make contact. There is actually a mopar youtuber that just had this issue on a recent vid- Junkerup chris birdsong- towards end of video