Originally posted by: skyjedi2005

years ago they were supposed to release full bitrate PCM audio versions of the trilogy on laserdisc under the THX laserdisc program sadly they were cancelled and never released.

IIRC, Raiders and TOD were among the "test" titles released without any mention of THX on the packaging. (The others were Apocalypse Now and Star Trek 6.) They were "unofficial" in that the final specs for THX Laserdiscs had not been decided on, but the widescreen remasters went through what became THX mastering. Not sure about Last Crusade, as it I think it came out in widescreen before the others.