We (Offroad Design) work on putting stuff on a 4L80 daily. 32 spline NP208 bolts right on to a 4wd 4L80. No mods required.
Figure 8 NP 205 requires an adapter housing (4" front to back) and a 32 spline input in the 205.
32 spline NP241 will bolt right on a 4wd 4L80 using the factory adapter...