For me it was all about the the effects. I bought a Boss Octaver, Super OD, and Boss DM-2 delay thinking they were essential to the tone. I also lucked out with my first guitar, an SG junior 67, with a T-bucker stuck in it replacing the P-90 dog-ear, and I bought a deluxe reverb new at the time (late 70's). That rig nailed the live dead tone to a T. I was never quite happy with the deluxe and SG for anything else, but it was decades before I upgraded to a PRS and twin reverb (2007), to chase a more modern sound.
You could read about Jerry's gear in Guitar Player, and any decent guitarist into the dead had a basic understanding of his rig. The effects were visible to the audience, they way he had them set up on stage, and they showed up in many of the photos being sold on tour.
The biggest curse ever for me was stumbling upon RUKind. Too many tones, too many options, and way too many ideas for gear to lust over is what the internet has brought us. But hey its all good!
I saw Max Creek down in Costa Rica last month. Scott plays a stock Ibanez Musician he bought new in the early 80's through a Vibrolux. I was chatting with him the day after the show when I ran into him on the street. He's got the right idea!
and I love his tone!