Stolen from another website,
In 1966 Mack introduced the Maxidyne engine,these engines were painted gold and all MAXIDYNE ENGINE EQUIPPED Macks had gold Bulldogs.Didn't matter what transmission,athough 95% of all Maxidynes had Mack transmissions,and it didn't matter what rear ends were. During the 1980 model year,Mack had to quit using the gold engine paint,but the gold Bulldog remained until 1981. By this time the 1st generation of Econodyne engines were being produced and the gold Bulldog went away until the early '90's they were brought back on the hood of the Elite package CH and CL trucks. Then in 95 or 96 they started putting them on the all Mack component trucks and this remains to this day.