Sup guys, I drive an 02 Ranger 4wd with a 4.0 L engine. When im driving, theres a loud rumble that I can hear. Even if I am just rolling down a hill with my foot off the gas, its a loud rumble. At around 45 mph, the rumble gets louder and sounds like my trucks about to break. I need some help on diagnosing it. I was thinking my rear diff is bad because thats also leaking or a bad drive shaft. Thanks in advance.