Some facts about the Mack truck; (from First Gear website)

In 1966, Mack Trucks, Inc. introduced the infamous R-Model series as their new conventional line of highway trucks. The R-series was an upgrade from previous Mack conventional cabs in that it featured a tall, almost vertical, two-piece wrap-around windshield and large side windows providing drivers with much improved visibility; a one-piece fiber glass hood and fender unit which tilted forward to provide easier access to the engine; double-wall, welded sheet metal cab construction; and improved instrument panel design. The tall cab gave the Mack R-Model the appearance of a much larger truck, when in reality it was the same size as its predecessor, the B-Model Mack.

Available engines in the R-Model included both gas and diesel powered, ranging from 140 hp up to 255 hp. In addition, by the end of 1966, after seven years of development, Mack Trucks introduced the revolutionary Maxidyne diesel engine that had the ability to offer constant horsepower. The Maxidyne had a peak rating of 237 hp at 1700 rpms resulting in significant benefits for both the truck and the driver. Such benefits included increased fuel savings, decreased effort in shifting gears, and lower transmission wear-and-tear.

With the introduction of the Maxidyne engine offering maximum horsepower over a longer rpm range, a new 5-speed transmission was also developed by Mack to complement this new engine. This Maxitorque transmission featured a triple countershaft which enabled it to be shortened considerably, as well as having the advantage of being lightweight.

The Mack R-Model had superb engineering details, which allowed drivers to "customize" their models to meet their needs. Throughout this R-series production history, Mack continued to upgrade and update the mechanical components of the truck. For this reason, the R-Model remained in production for an amazing forty years! And just as Mack Trucks allowed their customers to customize their models to meed their needs, First Gear is also pleased to offer additional options to expand our 1/64 scale Mack R-Model product line.

End of information that I downloaded.

This is one of those real and diecast trucks that I like.
It is also a truck that really changed the heavy haul / long haul truck manufacturing industry.
Thanks First Gear for making the 1/64 scale Mack R Model trucks.

P.S.: Steve (an old time friend), I still remember your first Mack Model R with the sleeper.

Cheers. Cobra