on the NV you'll need one with the speedo hook up, if you care about that sort of thing.
don't be lulled by the siren song of the ram version, the shifter is in a different place and makes that tricky.
the trans mount is probably going to be the biggest obstacle.
the gear splits are booty unless you've got gobs of torque. if you soft pedal it, you'll likely be fine. they weren't excact robust units.
you could probably do a T5 for about the same money and it'd be a lot easier.