Download ISSUE Some 2002-2005 4×4 Explorer 4dr/Mountaineer and 2003-2005 4×4 Aviator vehicles may exhibit a vibration/drone/boom at 55-75 MPH (89-121 km/h). Electronic vibration analyzer (EVA) readings will fall under 1st order rear driveshaft at 2700-3100 shaft RPM (45-52 Hertz). ACTION If the condition is present in 3rd gear (with overdrive cancelled), and is isolated to the driveline (not felt through the steering wheel), install a premium balanced driveshaft. Refer to the following Service Procedure. SERVICE PROCEDURE NOTE THIS TSB DOES NOT APPLY TO THE SOLID 4X2 DRIVESHAFT, IT ONLY APPLIES TO 4X4 WITH BOOT/SLIP JOINT IN THE MIDDLE OF THE DRIVESHAFT. 1. With the vehicle in NEUTRAL, position it on a hoist. Refer to Workshop Manual Section 100-02. 2. Remove skid plate, if equipped. 3. Remove the driveshaft flange bolts (Figure 1). 5. Using a suitable tool, disconnect the driveshaft flanges and remove the driveshaft (Figure 3). Figure 3 – Article 05-16-4 6. Measure the NEW driveshaft length from u-joint center to u-joint center. Refer to Step 6a or 6b. a. Driveshafts measuring LESS than 1194 ± 1.0 mm must be expanded as follows: (1) Place driveshaft on a suitable workbench and firmly secure either flange in a suitable vice.