Space Kaijuu said:

I got to watch Aliens in 70mm for a special screening. From everything I read, that one along with the original Terminator film were hard-matted. The 70mm print looked so much better than the Laserdisc release that was, at the time, the only way to get the extended version of the film but it had black matte bars along the edges since there wasn't enough picture information to take up the full 70mm film frame.

Yes, I do recall reading that both films were hard-matted. I've seen an original trailer for The Terminator projected open-matte, and I remember black bars on the top and bottom with fuzzy edges - I'm assuming that means the matting was done in-camera. (But amusingly, the animated lightning effects seem to have been shot using the entire Academy-ratio frame, because they extended out into the black areas, past the live action!)