This is my first post on this site so bear with me regarding my explanation. I have a 99 f250 crew cab short box 4x4 7.3 diesel. When I am sitting at a stop sign and hit the accelerator it feels as though something is loose under the truck. I just had the transmission rebuilt and beefed up with a heavy duty torque converter. The transmission shop says it migh be the shackles on the leaf springs being loose. Does that sound right?