can't copy and paste from mitchell on demand, but here it goes,
Some rear main oil seal failures may be caused by abraison from dirt or contamination, which can collect on the seal. Vehicle operated on dirty or dusty conditions are most susceptible to this type of failure. A rubber plug is now being used in production to eliminate an entry point of contamination. The plug is now installed in a one inch hole in the cylinder block, directly above the starter mounting location. The plug P/N 53020465, is available through MOPAR, and should be installed any time a rear main seal service is performed. This can significantly extend rear main oil seal life for vehicle operated in these conditions.
Just go to any dodge dealer and ask for the bulletin when purchasing the plug, can't copy and paste the exact location of the plug from mitchell.
Good luck, I'll be doing mine this summer.