Does the vibration go away when you have 4wd engaged? If not, you may have a cable problem to go along with your vacuum problem. But I would start by replacing the vacuum switch.

 

Cable and actuator under the battery tray are good. Actuator hold a vacuum, and cable moves freely about 3/4"

The actuator is collapsed or tugging or pulling the cable constantly. (In 4wd or 2wd)
Switching from 4wd to 2wd made no change in the cable. (Full vacuum going to the actuator)
Vibration was present in 2wd and 4wd.
No vibration when I unhooked the vacuum from the actuator and plugged the vac line from the transfercase. (or tranny, wherever the vacuum switch is)

 

You didn't answer my question....

The problem doesn't necessarily have to be the cable. It could be a problem with the engagement collar or something else inside the front axle.

 

Switching from 4wd to 2wd made no change in the cable. (Full vacuum going to the actuator)
Vibration was present in 2wd and 4wd.
No vibration when I unhooked the vacuum from the actuator and plugged the vac line from the transfercase. (or tranny, wherever the vacuum switch is)

I live in Utica, NY and rarely use 4wd. My main concern is getting rid of the vibration. I didn't try 4wd in my test but I can tomorrow.

 

I stand corrected, but I also stand behind what I said. The switch will likely fix the issue in 2HI only.

 

I agree