Old cars 630
Inherintly flawed 2-3 shift, that annoying TC drainback in park, poor pressure regulation in reverse, the direct drum bushing is way too thin and the direct drum wobbles around after a while, causing nice internal leaks. Use of a band for intermediate tends to aggrevate this even more. The low roller bearing support is weak as heck. There's no vacuum modulator which means if your throttle cable ever gets out of adjustment, the tranny stands a good chance of getting wasted *fast*. Overly complex band actuation mechanism - worse than the mess the C6 has.
The only reason anyone thinks the 727 was that great was they put it behind a Hemi. Big whoop, the THM400 went behind 454s, the C6 went behind 427s, 460s, etc. Of the 3, the 400 is the best, the C6 is a distant 2nd, the 727 is just behind it. The C6 is a clunky oversized unit, but about all you'll ever kill on one is the intermediate band (same problems as the 727). The 400 is smaller, shifts better, and is fine, save for the first 2 or 3 years where they were chasing center support issues. The ironic thing is the 400's gear train is a lot like the origional iron case Torqueflite, but Chrysler dumped that for the silly (but cheaper?) setup the 727 uses.
Old cars 631
Indeed. One still needs to use care around batteries. Wedding bands and watch bands make nice contact points. Some of the high power industrial bus bars of the day were...