I have a 1994 1/2 ton with manual locking hubs and a push button engager. About 4 years ago with the 4 wheel drive engaged, the front end would shake when i drove over 45. Then a couple years ago it started to grind and clunk when I made turns with it in 4 wheel drive. Now this year I went to use it, and it won't even engage. I'm probably a bonehead for not fixing it sooner, but what should I be looking at first when I pull it into my shop? Where can I get schematics on the gearing if I open it up and find a metal shard maze?

 

The pushbuttons on the dash only control the transfer case (ESOF). Read this caption:



The vibration is from the front axle. Click my black Bronco in my signature & read all the captions in the Brakes & Hubs album, and follow the links in the caption that lead to the diagrams of the front axle.