I’m experiencing a vibration when decelerating mainly over 50 mph gets worse the faster I go the truck is an 05 fx4 4.0 with an auto trans rear is a 4.10 track lock I got under it today u joints seam good there is maybe a little more then normal bask lash on the ring & pinion but the aluminum drive shaft has play in the slip yoke I can move it up and down and hear a clunk it’s like the splines have to much play could this be the cause and is it repairable or do I need a new driveshaft BTY the truck has 149 k on it any help is appreciated thanks