Since i bought my truck i have noticed it has bump feeling, its kinda hard to discribe. When i stop at a light, i feel a bump, when i take off i feel a bump. its like something has slack in it and dosnt catch until the truck is moving some. All my U-JOints are fine and my rear end dosnt have any slack. I can move the drive shaft up an down about an inch at the carrier bearing. Im not sure what this is and its very annoying. Could it be a bad carrier bearing? It hasnt gotten worse and it hasnt gotten better. Any ideas?