treegrower - The GM "MY6" overdrive transmission is designed to mount directly with a standard GM/Chevrolet bell housing pattern. The pattern of your pictured transmission looks like the "A833" MOPAR version of the transmission, which only fits MOPAR bellhousings I think.
The short tail shaft/housing is what clues one in that it's a truck model as most of the car model A833's had a long tail shaft/housing design.
On the shifter, from what I know of the MY6 and A833 truck units, used a specially designed shifter and rods. You might be able to use an aftermarket shifter and fabricate the needed rods and levers.
Here's a thread in another forum that has some great pictures and info on the
A833 4 speed shifter and linkage. Below are a couple pics from that thread extracted from a MOPAR shop manual that show the shifter on the truck style short tail shaft transmission.
If you are hunting for an original style shifter, look at ebay. There are some offered, but be forewarned you are probably going to get some sticker shock on the asking prices.
