Autos do NOT work well behind a diesel (the exception being the Allison, which is more purpose-built for diesels). Autos require line pressure to work properly- the higher the line pressure, the less chance of slippage (generally speaking). This works well for gas engines- they build power as RPMs increase. But most diesels build max torque at low RPMs, which destroys most autos quickly. This isn't as bad for the GM V-8 diesels, since they make their power at higher RPMs than inline diesels, but its still something to consider.
Add to that the fact that you are considering one of the worse autos GM ever produced. They went from very weak in the early years to marginal in later years. There are companies who can build them for a bit more strength, but you pay for the strength.
I really like my NV4500 that I swapped into my Durango (behind a 4bt Cummins). I paid $630 (including tax) for a low mileage used one, picked up the bellhousing and flywheel housing for $125, and bought the clutch & flywheel as a package from Napa. I think I had around $1200 (or less) into the whole transmission.
Too bad you weren't looking a little while ago, a few months back i was hurting for money so I sold a GM version NV4500, with the rare granny low (6.32:1) first gear for $400. That included the bellhousing.
Go to
Car-Part.com--Used Auto Parts Market to look for the trans. I got mine from a boneyard in Maine with warranty.
Jim