Manual Hublocks
WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Mechanical shift four-wheel drive vehicles are only available with manual hublocks. These hubs do not use a vacuum actuation system. Before diagnosing the hublocks for faults, be sure to eliminate all other four-wheel drive system components.