I have one of these New Process 833s (RPO code MY6) behind my GM 6.2L diesel.
It has a lot better drive ability than the SM465 granny low manual trans.
I have the 4wd version as well with the round-6 bolt adapter to tcase hanging off the back, but it needs a new input bearing retainer.
Here is a detailed article about it
http://zetan.cc/van/np833/
1975 thru 1987 Overdrive 3.09:1 - 1.67:1 - 1:1 - 0.73:1
The transmissions is rated at 270 ft-lbs. torque.