captainsolo said:

On Die Hard, it's mainly guess work. The 1st LD had the presumable 35mm Dolby Stereo mix with different effects and overall different general mixing. This is the same track that is on the THX LD as the digital track and the ac3 2.0 found on the later DVDs. (The first one was a direct LD port, and the later SE 5 star ones are just reworking of those same transfers. I'm pretty sure the 1st and 2nd film BDs also use this same general master, but heavily modified again)

But as far as if the original untouched 70mm version was released, who knows. Presumably the LD 5.1 in both Dolby and DTS versions is this, as would be the DVD iterations as they used the exact same tracks and video masters.

Back from Christmas vacation. Yeah I was on the LDDB and saw this from Disclord which agrees with you:

"BTW, the 70mm 6-track mix for Die Hard was done after the initial 35mm release - Fox wasn't sure of Bruce Willis' box office draw so no 70 prints were made until the first box office results started coming in. It's a beefed up mix compared to the original Dolby Stereo, with different sounds here and there, more aggressive panning to take advantage of the discrete tracks, etc. Grease was the same, with 'late' 70mm prints and a different mix".

I have this laserdisc:

http://www.lddb.com/laserdisc/10657/1666-80/Die-Hard-(1988)

I'm wondering if it had the old 35mm mix.