It's odd that on the 1991 WS LD of Jaws, some effects and dialogue are emphasized differently...this along with the alternate music inserted to avoid paying rights makes me wonder if there was some general tweaking done on the mono audio.
Sky, I've tried to find the Bullitt mono track for some time. Other than Beta or possible CED, we might have to go to a 16mm source. The current audio is derived from the LD track, a stereo-ized matrixed surround track that has no defined source. I have never seen anything other than mono for the film, as it was not a major event picture for 1968 and was not afforded anything other than a mono track.
Dirty Harry is stereoized or 5.1 on nearly everything.