According to Cross Between at deaddisc.com deaddisc, Garcia plays banjo on Flying and steel on Flotation and Reach High. More: "Garcia's contribution to this LP is not documented on the LP cover. There is simply a note on the back cover that says 'Special thanks to Jerry Garcia' ... It has subsequently been confirmed by Walter Rapaport, the co-producer of the album, that Garcia played on Flying, Flotation and Reach High. The contribution to Flotation is only 4 notes." Ed Bogas sometimes played keyboards, sometimes violin, not sure which he plays here.
ref: American Federation of Musicians (AFM) Standard Recording Contract between Robert Swanson [leader, signed] and Fillmore Corp, dated October 12, 1970, Wally Heider's Studios, October 5, 1970, 1:30-4:30 PM, AFM Local No. 6 San Francisco contract archives.