I had a vibration from under the truck and it was the front drive shaft. It was wore out from sand and no grease ( thanks whoever had it before me). Try to move it up and down and see if it has alot of play. I would try the cv shafts first then look at the idler arm and pitman arm.
I did it on my 92. find one with the same gear ratio. Find some u bolts, pads, rebuild the brakes . I lost my 92 z71 when the rear wheel brake cylinders quit on the 4th of july .