That there is a pedal steel guitar, Enthusiasts; specifically, a customized (of course) Zane Beck D-10 that Garcia bought in 1969. Two necks with ten strings, each in open tunings. Some pedal steels have only one neck, but Garcia was in the Grateful Dead, so we should probably just be glad he didn’t order one with nine necks.
The pedal steel guitar has more in common with Brent’s Hammond B3 than it does with Wolf or Tiger. All of your limbs are involved; in fact, one leg does double duty. Your right foot controls the volume (like the B3), but you need to use your left foot and knee. The three pedals lower the pitches of the strings, while the knee levers raise them. The slide goes in your left hand; picks on your right fingers; mute with your right hand. The upper strings of a double-necked guitar are usually tuned to E9, which looks like this: B-D-E-F#-G#-B-E-G#-D#-F#. Plus, if you were Garcia, you had a cigarette to manage.
I can’t imagine why he stopped playing the thing.