In the early 90's I was working at an animation studio Rocket Productions and we were commissioned by Alan and Ray Whitfield Ford to redo their classic "Duke & Dawg" animated commercial. (Most Detroiters my age know that indelible song that Duke sings!)
Apparently the original animation was damaged beyond repair so they wanted to redo the whole spot with a new beginning of Duke talking and some antics by Dawg. They were emphatic about making the revised commercial look like the original. I animated and cleaned up the whole spot myself. It was done the old fashion way by using paper, cells, ink and paint. Subtle embellishments were made within the animation by tightening up the lip sync, having Duke's fingers playing the banjo and adding more inbetweens.
Revised version that I animated: