This isnt an fbody but I'm having trouble with what i think might be coming from the engine/tranny or rear axel. When i start picking up speed its kinda like the rear end just keeps jerking back everynow and then. Sometimes it gets really bad at stop lights when it does this and the whole thing starts shaking really hard. At first i thought it might be because its not wanting to change gears because after all it is a jeep tranny(even tho its a new one and has a warranty). Then i thought it could be a mount is missing something or maybe the rear axel is messed up but idk much about those. Any ideas on what it could be? The engine is a 318 5.2L (Basically a magnum without the name) and its 4wd. Im selling it soon anyways tho when i get my fbody but its gonna be hard to sell something that does that.