Here I'll just mention a few things that have not traditionally been represented there regarding Garcia's work with Stephen Stills. This information comes from an interview with Jerry conducted, I think, in March of 1981 and published in the amazing British 'zine Swing '51 (1). Both quotes are from page 26.
Regarding Stephen Stills 2, deaddisc has traditionally said that "Garcia possibly plays pedal steel on one track." Matt has now included what follows on the site, but unless Jerry is talking out his ass it doesn't sound like there's much doubt about what's what. Here's what Jerry told Ken Hunt of Swing 51: "that's me playing pedal steel [on 'Change Partners'] and there's an uptempo tune on that LP that I played on." Steve Silberman has told me that Change Partners is a well-known Garcia appearance despite being uncredited, though I don't know where things stand in terms of the "uptempo tune" that Jerry mentions (nor which tune it is - I don't own the album yet).
Regarding Manassas, deaddisc has recently included this Garcia quote from the Swing 51 article, though indicating that things are still uncertain: "There are a couple of tunes on there where I play pedal steel and maybe even guitar on one, but there's at least two that I'm not credited on. But I did the sessions and it's me playing." Silberman is much more enthusiastic about this possibility, suggesting that has been previously unknown. He also reports that while Al Perkins probably did most of the (and arguably the finest) steel work on Manassas, the style suggests that Jerry might well be playing on "Jesus Gave Away Love For Free."
We may never know. Garcia describes working with Stills in the studio in this way:
Sometimes they were very weird experiences. Like, for [Stephen Stills 2 and Manassas] I didn't know what records they were for or anything. The way Stills worked at the time was he just accumulated endless tracks. He worked on dozens of tunes. He actually flew me into Florida for a week, me and Ramrod, my equipment guy, with my pedal steel and guitars. I went down there and did sessions at the weirdest hours! Stills had two teams of engineers, two shifts. The way he worked in the studio was totally crazy. At the time he was really happenin', really doing well, could afford it easily. They were not only studies in over-indulgence, but there was some pretty OK music too!
Anyone know the dates that Jerry was down in Florida for this? :)
Anyway, as is the typical MO here, I am mostly just putting this down so I don't forget it. Best thing about a blog, far and away.
Hunt, Ken. 1983. Jerry Garcia: Folk, Bluegrass and Beyond [part II]. Swing 51 no. 7: pp. 22-28.