Several years ago (like nine) I started a thread about whether a track by Bobby Lance called "More Than Enough Rain" featured Dune's slide work. You can find the original thread here:

http://www.allmanbrothersband.com/modules.php?op=modload&name=XForum&file=viewthread&tid=40191

Here is the track:

Opinion was pretty much split on the issue with the majority leaning toward it was not Duane. Even so the track does appear on Skydog: The Duane Allman Retrospective with the liner notes still very speculative.

Just recently Bill Kopp a music writer who did a special assignment on Bobby Lance contacted me. Here is the relevant quote regarding Duane's participation from his article on Bobby (now Bob):

Though it has been the subject of speculation for decades, Lance vigorously confirms Allman’s presence on “More Than Enough Rain.” The chronology of Allman’s involvement goes like this: Bobby had self-produced the sessions for First Peace, but remained dissatisfied with the completed mixes for a few of the album’s tracks. Ace producer Tom Dowd offered to remix those tracks, so Lance traveled to Dowd’s Miami, FL Criteria Recording Studio (also known as Atlantic Records South), bringing along the multi-track master tapes. Under Dowd’s supervision, Lance overdubbed some vocal tracks, and left the tapes with Dowd. Soon thereafter – October ’70 – Allman was at Criteria for the sessions that would produce Ronnie Hawkins‘ self-titled 1970 LP. In a spare moment during those sessions, Dowd asked the guitarist to lay down some licks to improve Lance’s track; the resulting mix of “More Than Enough Rain” features musical sparring between King Curtis’ horn lines and Duane Allman’s impromptu yet fluid slide guitar work.

You can see the entire article here:

http://blog.musoscribe.com/?p=7188

As Eddie Hinton is the guitarist on the remaining tracks, I asked Bill whether he might also be playing on this track. His response, "I’m not sure about whether Eddie laid down a part, but it’s certainly possible. Maybe what we’re hearing has both of ‘em. Not the likeliest scenario, but definitely not beyond the realm of possibility." This may account for the difference of opinion on whether or not this is Duane's playing.

As a sidelight Bill's article makes clear that Bobby Lance was one of Atlantic's hidden (and unpromoted) gems. Worth a listen as his two albums are now back in print.

BTW, Bobby's biggest musical claim to fame is as the co-writer of Aretha's "The House That Jack Built".