Change from 4-speed to 3w/OD

RustyRatRod said
No, you want to change from a four speed to a four speed OD. The Chrysler four speed OD transmissions still carry the A833 designation. That means they are a four speed, not a three speed. If it has four forward gear, it's a four speed. I never understood why people incorrectly call them 3 speed over drives. There were three speed over drives made, with ONLY three forward gears and high was OD. But the A833 tranmissions are ALL four speeds.

You will need a different bellhousing or you can have yours possibly machined to fit the larger 5.125"bearing retainer in the OD transmission.

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.