According to the Herb Lubalin Study Center of Design and Typography, this logo for Mountain Dew was proposed by the Lubalin studio probably sometime in the 1970s.
Mountain Dew is a soft drink brand using a formula originally invented in 1940. In August 1964, the brand and production rights were acquired from the Tip Corporation by Pepsi-Cola. In the late 1960s, Mountain Dew still used the so-called Hillbilly logo. By around 1970, it was discarded in favor of psychedelic lettering, with the two words stretched to fit into a rectangle. The accompanying “ya-hooo” wasn’t deleted from the logo until about 1975.
The logo proposal is based on the solid style of Algonquin. Originally designed by John F. Cumming and advertised by Dickinson in 1890, New York-based Photo-Lettering, Inc. showed a phototype adaptation of both styles in their 1971 One-Line Manual of Styles.