Over the last couple of weeks I did some web searches and had a chance to hear Mike McLean's disk-to-disk copy of the version that landed at Motown. Unfortunately I didn't come away with much in the way of answers, but here is what I can report.
It seems that many acetate versions of "A Day In The Life" circulated.
Brian Epstein played one at a get-together in New York.
http://64.177.126.79/articles_epstein.htmPaui McCartney visited Brian Wilson during the recording of the Smile album, and played one for him.
http://earcandy_mag.tripod.com/rrcase-1.htmJackson Browne recalls hearing an acetate on the radio, before the album was released.
http://www.superseventies.com/ssjacksonbrowne.htmlI saw many references to "A Day In The Life" acetate versions that wound up on bootleg records -- particularly, a bootleg called "Acetates" on the Yellow Dog label.
http://www.geetarz.org/reviews/beatles/acetates.htm.
From the descriptions I read, most of the bootleg versions differ substantially from the commercial release, although Mike's is very close. When I A/B'd his recording against the album I couldn't hear any differences in the performance or the mix (which is mono), except for the beginning and end.
The beginning doesn't segue from sound effects like album version does. (Terry said the same about his recording.)
The end is much shorter. Mike's disk times out at 4:33, compared to 5:33 on the CD. The song itself is the same, but the decay of the orchestral climax is only a few seconds long, versus half a minute or more on the release. The ending on the CD has a few seconds of 15 KHz tone ("especially to annoy your dog - at the request of John Lennon", per the liner notes) followed by a few seconds of chatter and nonsense. My Capital LP has neither.
As a further step in all this scientific testing I brought my dog into the shop and played the end of the CD, rather loud. During the HF tone (which I measured at 15,038 Hz) the dog yawned, not interested or annoyed in the least. My wife heard it though, and was annoyed. Actually, she found this whole project annoying, and suggested that my time could be better spent on something else, like helping with yard work. Oh well.
Google had several hundred hits to sites that mention bootlegs and acetates of "A Day In The Life", and I'd hoped to find something that specifically answered this, but the most intriguing links just pointed to this thread. (Google is fast.) If Terry has a chance, maybe he can play his tape copy and see whether it agrees with my description of Mike's recording. If there's an answer out there to this mystery, I wasn't able to find it!