I have a 1999 Mercury Mountaineer (i.e. explorer) with 4-door, AWD, 5.0L engine, and ~170,000 miles. I am hearing a squeeking from the rear of the car and am going to change the U-Joints. I noticed that the u-joints do not actually have much play/slop.
However, the driveshaft has perhaps 1/8" of slop that I can shift it up and down on the gear inside the transmission when the car is in neutral. It seems like one or both of the gears (transmission, driveshaft) are worn out. Is one made softer to be the "wear" part (hopefully the drifeshaft)?
The car also has more vibration when I am on the highway and let off the gas to coast. My logic is that perhaps the vibration is being caused by these two loose gears banging around on each other when I let off the accelerator and coast.
Any experience on how to figure out if only the drieshaft, or both parts, are worn would be much appreciated. The problem now is not really much more than a vibration sound, but given the slop in the gears, I don't want the problem to get much worse because I did not take action in time.