The Laserdisc FAQ mentions 44056Hz PCM. It's probably where I read it first.
Author doesn't say anything about AC3 sampling rate, so my hypothesis is still a WAG . . . but it makes perfect sense in my mind.

When film is shot, live action is sampled at a rate of 24Hz by the camera.
NTSC plays it back slower than that, by a factor of 1000/1001

When PCM is 'shot', analog sounds are sampled at a rate of 44,100Hz
NTSC plays it back slower than that (44056 if the FAQ is correct)

When AC3 is 'shot', analog sounds are sampled @48kHz then DD-compressed.
NTSC plays it back slower than that ???

I'd test the hypothesis using a hex editor to manipulate the WAV header...

... or force video playback to 24.000 and see if the 48kHz WAV syncs to that