Not sure what year and trans you refer to.
NAG1 is the same trans regardless what engine it is behind except the converters have different k factors.
The 8 speed is available in 70,80,90 configurations. I think the 8HP70 is behind all passenger cars until you get the Hellcat which if I recall is the 90.
Truck gets either the 70 or 80 depending on engine.
The bellhousing area is the only clue that I can recall to ID them unless you look at casting numbers and such. But I have been away from them over a year now.