Borrowed from an Outside article on AWD vs. 4WD, here’s a lovely vintage video on differentials. (You can safely skip the motorcycle sequence to about 1:56 though it’s pretty interesting. We used to be much easier to entertain.)
EDIT: Extra credit if you know what they used to mock-up the differential.
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-Don-
Life and baseball both sometimes are not fair, but it is how you play the hops that counts. —Scott Miller, NYT Sports
I've seen that video a few years ago---its interesting.
Seems like everything on YouTube has some sort of musical lead in or accompaniment; sometimes too loud at first start up, most times far more annoying than the creator realizes.
The motorcycle stuff kinda typical for that period---still love seeing all that vintage iron.