Strings were removed from 'Fool' before release, although some strings can still be heard on the released master of 'Fool' .

The undubbed masters on Our Memories Of Elvis weren't really the pure undubbed masters. They were the fully overdubbed or regular masters but with certain instruments and backing vocal channels removed or stripped down.

An edited (2:21) version of 'Burning Love', with omitted part of verse ("Help me I'm flaming, I must be a hundred and nine, burning, burning, burning and nothing can cool me..."), was released in 1987 on the BMG Ariola release The Definitive Country Album.

Takes 5 and 6 of 'Burning Love' can be found on the Venus bootleg Unedited Masters - Hollywood To Nashville 1972-1980 although Take 6 contains overdubs, as the overdubbed cowbell and additional guitar can be clearly heard.

The re-recording of 'Burning Love' can found on the 2015 album If I Can Dream, which contained Elvis' original vocals but with new backings by The Royal Philharmonic Orchestra, and which actually went to number one in the UK album charts.

An extended version of the already edited master of 'Fool' , with strings, can be found on the cassette version of the Elvis Aron Presley box-set.

There appears to be some controversy regarding the different mixes of the song 'Fool' released on FTD's Elvis (Fool) classic album.
The mix of the song on FTD's Elvis (Fool) (track 14), FTD's Standing Room Only, Elvis (Fool) (1994 CD) and Elvis (Fool) (original LP) appear to be the same.
The mix on track 1 on FTD's Elvis (Fool) appears to have a different mix (0.5% faster, more echo, the instruments themselves aren't so clear as on the other mix, and the vocals are slightly more on the right).
I think that track 1 on FTD's Elvis (Fool) is the original alternate mix and should have been placed as track 14, and that track 14 on FTD's Elvis (Fool) is the originally released mix and should have been placed as track 1.
Basically, they're reversed!

In March of 2007, Sony decided to go through all of Elvis' masters. They retransferred everything and remastered all tracks including repairing as many clicks, pops, bad edits and dropouts as they could. They have used these newly mastered recordings on their new releases since 2007 including budget soundtracks, Legacy releases, the 30 disc Complete Elvis Presley Masters collection and the Franklin Mint package.

Thanks to Luuk Bonthond regarding extended versions of songs on the cassette version of Elvis Aron Presley.

Thanks to Adrian V Stokes regarding the edited versions of songs on the BMG Ariola set of Definitive albums.