Thanks. That was new to me too. 

Jeff Hanna of the Nitty Gritty Dirt band in a recent interview discussed how much he was impressed with Hourglass and Duane Allman's guitar playing in particular seeing them several times at the Whiskey A Go Go. 

Jeff became good friends with Duane and got aquatinted with Gregg too. 

But Jeff said oddly when listening to their two Hourglass albums you didn't hear any guitars solos from Duane that stood out and stretched out or any of the hot blues tunes the band played live. 

To correct this Duane took the band to Muscle Shoals I think it was and recorded their third album there with lots of lead guitar and blues tunes. They presented the tape to Liberty as their third album and Liberty refused to even listen to all of it and it wasn't released. Duane said screw the contract I'm quitting. Liberty said fine as long as your brother stays and records the third album with the songs we want on it as your bother is actually is the only member of this band we like and think has a future in record albums. The rest of you guys are welcome to leave. 

Gregg was forced to stay in LA to keep the band from being sued and recorded the third album which included a version of Tammy Wynette's D. I. V. O. R. C. E. 

But Liberty decided not to put any more money behind the session and it wasn't released. 

To Gregg's embarrassment ( Gregg said in an interview I read back then he was embarrassed and told his fans NOT to buy the album) some of the tracks did appear on an archival Hourglass release after the Allman Brothers Band became famous. 

The only thing that could top Gregg Allman singing Tammy Wynette's D. I. V. O. R. C. E would be Tammy Wynette singing Whipping Post. 

Actually Gregg's voice is good on his version of D. I. V. O. R. C. E.  

Someone at Liberty Records decided that should be on Gregg's session to finish out the three album deal. 

At least they didn't have Gregg sing " Tiptoe Through The Tulips" or " Shine On Harvest Moon 🌙".