I got both the coolant flush and differential fluid change processes by searching this forum. There were several coolant flush threads. The Differential is pretty easy. On my 300E, the top plug was on the top left of the differential from the back facing forward. I made sure I could get that off first (if not, and you drain it, how would you fill it?). Once I did, I took the drain plug off on the bottom right and drained it. Put that plug back in and used a pump and hose I got from Autozone to pump in the gear oil back into the top left hole until it started coming out and put that plug back in. 10 minute job.