My summer job for four years in high school and college was working in the local Coca-Cola bottling plant, loading and unloading trucks like this one. There were no high-loaders or lifts, it was all done manually. To load a row of cases in the top rows, you had to climb up the side of the truck and push with your foot, since the row was too heavy to push by hand (at least for me). To unload empty cases, you could usually push the row by hand, but you still had to climb the side of the truck to grab them, depending on the height of the truck and how tall you were. Then, after unloading, all the empty cases had to be sorted by hand: all the Coke bottles in separate cases, all the Pepsi bottles in others, etc. Sometimes you'd find "strange" things in a returned empty bottle, e.g., a dead mouse or a cigar. One of the job's benefits was free Coke, all you wanted, and you soon learned that not all Coke tasted the same. The best was "post mix", the syrup used in fountains, where the syrup and carbonated water were mixed on the spot. Next best was "pre mix", where the syrup and water were pre-mixed in large metal cans, for businesses, county fairs, etc. The last was regular bottled Coke. This of course was in the days when Coke contained cane sugar, not high-fructose corn sugar. I thought I had the best summer job in town.

In later years, Dr Pepper eliminated the 'period', and the tag line became 10 - 2 - 4.
Those were the optimal times for the beverage.

Then empties are picked up and loaded.

The oldsters among us will know that those old time glass bottles, despite their inconvenience, gave one the best burst of flavor one could receive from a bottle of soda without the metallic tones of aluminum or the chemical betrayal of plastic. I fondly recall that at large summertime picnics usually put on by community groups, religious and ethnic clubs when I was a child, we always looked forward to the individual glass bottles of frigidly cold, fruity, delightful flavors and colors seen in those huge galvanized tubs containing vast amounts of crushed ice and nestled within that ice, like jewels, were tantalizing glass bottles of vivid lime green, bright orange, red cherry, purple grape, root beer and other tempting choices to enjoy with one's hot dog or burger. Since my siblings and I were always expected to share a single quart bottle when we were at home, at these special affairs we would each get our very own and would often drink ourselves silly. There really is something sensory and unique about a crystal clear, frigid, refreshing flavor from a glass bottled beverage on an oppressively hot, sweaty summer afternoon. Just another memory from the "long-ago" that will never come again.

"How come you're not in the service, mister?"

[Answered here. -tterrace]