According to one source and to DaShiell, Greenbaum used a Fender Telecaster with a fuzz box built into the body to generate the song's characteristic guitar sound.
Moreover, DaShiell explained how he created the song's distinctive "beeping" fills:"I actually played the lead guitar parts on Spirit, using a 61-62 SG Les Paul, a 68 Marshall Plexi 100w half stack and a home-made overdrive box in front of the Marshall.
Regarding the 'beep beeps' as I call them, when the producer asked me to play some fills in between the verses, as a joke I said how about something spacey like this and I did the pickup switch/string bending thing.
I saw him stand up in the control booth and he said "that's it! let's record that!" so we did. (There was no slide involved, just my fingers, and I used the bridge humbucker and the pickup switch).
The fuzz part is Norman with a built-in overdrive circuit built into his Tele pickguard.""I've been asked a lot over the years how I did the 'beep beep' guitar parts on Spirit, so for any guitar players out there who would like to learn how, try the following: Using a 2-pickup Gibson, set the neck pickup volume to zero, bridge pickup volume to max, with the pickup switch in the middle position (with Gibson wiring this gives you silence in the middle position).
Do a string bend, picking the B & E strings together with one hit, just ahead of the beat, then use the pickup switch to kick in the bridge pickup in triplets (6 per bar) as you let the B string bend down two frets.""I mainly used two positions on Spirit, which is in the key of A. For the low position, fret a stationary C note (8th fret) on the E string while bending the B string up to an A note for your starting-position, then pick the two strings together once while the guitar is silent and work the pickup switch as you let the A note bend downwards to a G.
For the high position, do the same thing at the 15th fret holding a stationary high G note on the E string while bending down from E to D on the B string.""I must give credit to Jimi Hendrix as my inspiration for this technique (as well as for the double-string riffs I did at the beginning of the Spirit solo tail section). I saw him perform live in a small club in Madison, Wisconsin and loved the way he used his Strat pickup switch to create staccato feedback on songs like Voodoo Child.
The difference is, on a Gibson you can start from silence and create the on/off effect, which worked well with the downward string bending thing I did on Spirit."The resulting sound was an innovative and compelling combination of gospel and psychedelic rock music, with loud drums, distorted electric guitar, clapping hands, and tambourines.
The production team brought in the Stovall Sisters, an Oakland-based gospel trio, to sing backing vocals. Because of its unusual lyrics and style, the record company was initially reluctant to issue it, but was finally released as a single after two other singles from the album had poor sales. "Spirit in the Sky" became a worldwide hit, and was at the time the best-selling single ever for the Reprise label.
Of the song, Greenbaum observed: "It sounds as fresh today as when it was recorded. I’ve gotten letters from funeral directors telling me that it's their second-most-requested song to play at memorial services, next to 'Danny Boy'."