Change from 4-speed to 3w/OD

dodge71demon said

From Allpar
Chrysler described the change as “an A-833 four-speed transmission, converted over to a three speed manual transmission with an overdrive gear ratio.” It was used with both the 318 V8 and 225 slant six. After the 1975 run, Chrysler switched to a finer-pitched gear tooth design to reduce the noise of the 1975 models, and changed the overdrive from 0.73:1 to 0.71:1. It used a steel housing except on the Feather Duster and Dart Lite, where it had an aluminum case and extension housing.

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Except, there's all kinds of inaccuracies right in that statement. For example, sometime after '75, maybe '76, ALL of them had aluminum cases. Only the '75 A body 833OD's were all iron case, and at some point they switched to aluminum main cases with iron extension housings, then all aluminum. There are tons of later truck 833OD's with the long b/e style extension housing that are all aluminum. The gear ratio change wasn't by year per say either, it was by application. Trucks got the .71 overdrive, cars kept the .73 overdrive. They kept the 833OD around longer for trucks, so again at some point all the 833OD's transitioned to the .71 overdrive, but it wasn't right after '75.

Allpar is nice, but it's not a "written in stone", 100% accurate source for everything.

Better info on the 833's and 833OD's here 4 Speed Transmissions transmission

As far as what to call it, do you call 5 speed transmissions 4 speeds with overdrive? How about a 6 speed like the T56? Is that a 4 speed with dual overdrive? Nope.