While Larry may have played tambourine part for "Slip Away" live, on the Broken Arrow album, Billy Talbot overdubbed the tambourine part in the studio. I believe he even gets a credit on the album. This is from an interview with Billy in 1996:
Click on the pictures of Neil to go to the interview, and the bit about "Slip Away" is on the 2nd page of the interview. Thanks to Hyperrust for the link!
Ned
PS. Joe Yankee played "electric tambourine" on Ambulance Blues... I know who Joe Yankee is, but I'm kind of wondering what an electric tambourine is. Another of Neil's jokes?