I am researching the manufacture of my 3 speed column shift transmission in my 1979 Dodge D100 with slant six. I want to place an overdrive unit on it. Cannot seem to find out. Any ideas? Thanks. Tony

do a search for overdrive four speed trans here on board ...they came in many pickups what you will need is flywheel,bellhousing,clutchfork,trans ,driveshaft(atleast front yoke) ,shifter/rods and tower for on floor(just screws in place)

Normally I'd make the assumption that 3 spd column shift means you have a 3 on the tree manual transmission wrather than the column shifted
3 spd automatic...

If you in deed have a 3 speed manual it will be a bit simpler...you will possibly need a new bellhousing (if the starter is a low mount), the A-833OD transmission/shiftrods/shifter.

-D.Idiot

the OD bell is different has larger center hole and different bolt pattern

The bean counters in 1975/1976 were tired of 2 bellhousings (For trucks that makes 3-11" clutch low starter NP435, 3spd only, A-833OD)By the late 70's the 3 spd bellhousing was no more, they fitted the 3 speeds with 'adaptor' bearing retainers so they fit in the "two pattern" OD bellhousing, this affords the 5.125" retainer fit, but allows it to be bolted to the smaller bolt pattern seen on all 3-spds, and the regular A-833 tranny's (those with the 4.8" )...making these retainers the $$$ junkyard adaptor item.

That being said, the possibility does exist that if it's not the original 3 speed for truck (previous owner paste and swap special), that it could have an earlier bell and tranny in it currently.