Blitter sent me a sample of his recording from the Stuart engagement so I could work up some comparisons with the original 35mm mix and the DC ’93 mix (derived from the 70mm 6-track). I equalized the 3 samples to roughly match one another. They can be found here:

http://www.yousendit.com/transfer.php?action=download&ufid=54CC09C5233B3C5F

http://www.yousendit.com/transfer.php?action=download&ufid=3972BE1324786728

http://www.yousendit.com/transfer.php?action=download&ufid=1DE255E717658F66

I'm quite certain this was from a 35mm print with no matrix decoding (which is why there is dialogue in the left and right channels). In the “70mm” file, one can clearly hear a pronounced explosion from the left channel that is absent from the 35mm file as well as the Stuart file. (This was in the original 6-track as well – not an addition to the “93 mix.)

It's quite possible that the Stuart had 70mm capability at the time, but likely did not have a Dolby processor and were unable to secure a 70mm print (legend has it that only 9 were struck for the initial engagement).