vmx120

I have a 1991 f150 lariat 4wd with 5.0 efi. Ran great initially, then one day,, as I was coming up to speed on the highway it started to vibrate at around 55mph. Backed off to 50 and it went away. I figured it was a ujoint about to blow apart. Got underneath and did my best to see if it was a bad ujoint. When I drove it again I can feel the vibration through the 2wd/4wd selector shifter. So now I am figuring it is my transfer case. What I discovered was if I turned the front driveshaft back and forth I can hear a distinct clicking coming from the bottom of the transfer case. Any ideas?


Thanks