mystery 4 speed

Should be an 833OD. Similar to the 833 but 4th gear is .73:1 or .71:1. It came in cars and light trucks, and it will be the long tailshaft style 833 with 2 shifter mounting pads.

Can be used in E bodies by using the rear most mount, B bodies by using the forward mount (although its not exactly in the right place). It can be used on A bodies as well using the forward shift pad (again not exactly the same location as the original A body shifter). You'll need to have the drivehaft shortened significantly though because of the longer tailshaft on the transmission.

Gear spacing is pretty wide because of the overdrive 4th gear, 3rd is 1:1. Good transmission for a street car though, as you can run decent gears and still cruise on the freeway. Not really good for any kind of racing though, as the gear spread is very wide.