Seventy years ago, it was starting to look like those newfangled 33 RPM LP records, as well as 45 RPM records, were going to catch on after all. But that handsome radio-phono console in the parlor only played 78’s. Fortunately, a kit was available to add those new speeds. You purchased a new record changer, which came with a mounting board with precut holes to accommodate the new changer. You measured the old board, and cut the new one to fit the cabinet. Connecting the power and phono input were then simple. Depending on which cartridge the new player had, you might also need to add a preamp.

This guide appeared 70 years ago this month in the April 1955 issue of Popular Mechanics.