I love your youtube channel, and thank you for your explanations..I have a question for you. I have a Ford Edge 2008. When I'm driving forward 40 Km/h for instance, and then stop and I change immediately to R gear, it sounds a heavy knock on the back differential I think so. For avoid this situation I always have to wait for 5 seconds between changes D and R. I think is a synchronization issue or something like that. How occurs this and how can I fix it? Best regards from Colombia!

if noise comes from back, first check for bad U joints on the drive shaft and pray it's not a worn differential. https://www.youtube.com/watch?v=xqSwmwUfoLE

Thank you very much!