Yeah, I am working on a little version history and that was something that just occured to me. I know there was 16mm prints to be seen in libraries around 1978, but if those were the same cut Silver has is anyone's guess.
VERSION HISTORY
When THX 1138 was originally released in 1971, it was in a hacked apart - 81 minutes long version after the studio Warner Bros had taken the film away from George Lucas and cut 4-5 minutes from it, mostly scenes in the "White Limbo" and some of the films bizarre humor were taken out, in addition, Walter Murch's sound design had also been altered.
Even though THX 1138 was released in UK and France in 1971, it wasn't released in Italy until 1976, then under the title "L'uomo Che Fuggì Dal Futuro" ("The Man Who Escaped From The Future"). How much this cut resembles the "Warner Bros-cut" released five years earlier in terms of editing is hard to tell, but both are approximately 81 minutes in lenght. This version opens with a flashback sequence narrated by THX himself. In addition, the usually excellent Italian dubbing in films is sometimes very poor and even alters the story in more than one way. In comparison to the later released restored cut, it includes a slightly longer "SEN talking with kids sequence" and re-ordering of scenes. This editing could very much be a leftover from the "Warner Bros-cut", but the other story differences that occur in the dubbing is more likely liberties taken by Societa Italiana Distribuzione Films which was the distributor for it in Italy. This was the only version available on video in Italy until the "2004-Director's Cut" was released.
It wasn't until after George Lucas' enormous succes with Star Wars in 1977 that Lucas was able to finally release a fully restored cut of his THX 1138. This version restored the previously cut scenes, making it approximately 86 minutes in length.
A German televised version and an American/English 16mm print has revealed that yet another version exists, it is almost identical to the original restored cut but it includes the slightly longer "SEN talking with kids sequence" and the same re-ordering of the arrest, seen in the Italian version.
THX 1138 was finally released on video rental in 1982, it was then in the form of the original restored cut. This version was widely available on Betamax, VHS and Laserdisc, the last release was on VHS in 1996, it has not yet been released on any new formats.
Finally in 2004, a new version was released in theaters for a limited time and released on DVD and later Blu-ray under the banner "The George Lucas Director's Cut". This version is approximately 88 minutes in length, have a much different editing which even alter the story in subtle ways, using alternate takes etc. In addition to using modern CGI, Lucas shot new footage for this version and even reshoot several scenes using computer systems to insert the actors and replace existing footage.
Have I missed anything, how is my English, can I complement with anything?