CONVOY's Rubber Duck
In 1973, Mack made several design changes to the R-model family. While a number of changes were made, we will outline some of the key visual differences which distinguish the Western R Models as either Pre-73 or Post-73 models.
The R-model "Command Cab" was changed in 1973 in two key ways. First, the rear wall of the cab was extended back 6 inches to allow for greater seat travel and driver comfort. The Pre-73 cabs had a nearly vertical rear wall, while the Post-73 cabs had a more defined curve shape to the rear wall.
The second revision was to the dashboard of the cab. The Pre-73 models featured an all-metal dashboard with a modest gauge and instrument cluster surrounding the steering column. Additional guages and dash accessories were placed randomly in the flat metal dash near the windshield center post. The Post-73 dash was dramatically improved, with a plastic shell and dramatically increased curve-around dash with large areas for extra gauges and controls. The HVAC unit below the dash also was updated with more user-friendly controls and additional vents. In the movie CONVOY, the interior of the Pre-73 cab can be seen in the final bridge scene. At the moment when the truck "turns" off of the bridge into the river, an interior shot clearly shows the old metal dash, especially when played in slow motion. Several other frontal approach scenes on the bridge show the old cab with the small guage cluster bezel visible through the front windshield.
This picture, of a 2002 Mack RD cab interior shows the Post-73 dashboard relatively unchanged. As a sidenote, Mack changed the guage design and indication lights in March 2001. The new style is shown.
1973 also brought about a change in the hoods for all Western Macks. Previously, Westerns used the same shell as the non-westerns, with a higher mount. The enlarged grille area in most models "spilled over" onto the bumper. Earlier models had a cut out at the top center of the bumper while later models of the pre-73 variety had a two-piece griller surround. Pre-73 RS700L/RL700L's had a unique step between the rear of the front fender and the battery box. The step consisted of an aluminum step box with 2 circular holes in the side and a stirrup-type step below the box. Also, many pre-73 RS/RL's had a chromed plate on which the trademark bulldog hood ornament was mounted. Due to the use of the standard R series hood, the fenders sat noticably high in relation to the steer axle.
The Post-73 hoods used on Western models were unique to the Westerns. Although the RS700L/RL700L's were discontinued in 1978 and replaced by the Superliner RW700 series, the RS600L/RL600L's were produced up to 1990, taking on the name of ValueLiners in the 1980's. These new Western hoods had a few unique characteristics which may not be immediately apparent to the casual observer. First, the fenders were lowered 4 inches, resulting in a vertical length of hood added just below the contour line on the side of the hood. The fenders also were shaped differently at the rear, as if they had been saw-cut at the top of the battery box/air tank assembly. From the front, the Western hoods had a slightly larger grille and surround. Also, the lowered fenders and wider grille gave a unique face to the Westerns, with respect to the manner in which the hood outline framed the grille surround.