Here's the back of the headstock, on at least its third set of tuners. Originally, Leonard would have been fitted with budget Kluson tuners. Nickel-plated ribbed rectangular cases with ivory-colored oval celluloid buttons.
At some time in its past (probably because the celluloid had rotted), some good-meaning but cheap soul had replaced the Klusons with a set of cheap open-backed Japanese tuners. These have parallelogram-shaped bases and are mounted with two diagonally-opposed holes located on the points of the parallelograms.
These are the holes you can see at upper left of each of the current set of Grover open-backs. These are quality tuners with vintage appeal, but are not correct, strictly speaking.
The finish (nitrocellulose back in '56) was worn off most of the neck and headstock. That's bare wood showing. It's too hard for basswood, the wrong color for poplar, though it does feel like poplar, so I imagine it's a softer cut of maple. Nothing exciting going on, grain-wise, either.