GM had all sorts of names for the early transmissions, most likey it's a version a super turbine 400 [or 300] as the real 3spd TH400 wasn't offered in a Cadillac until 1964, speaking of olds, some of the 350 rocket blocks bare weighed 198lbs, 394 is closer to 210-220 if I remember{?}
All the Trans you named there have torque converters & are fully alluminium cased, The trans in the video is a Hydramatic 315 (Jetaway) it has no torque converter & the main case is iron, very different from the ones you mention.
