GM 6L80E / 6L90E 6 speed automatics to the GM NP205 Figure 8 Transfer cases

This adapter kit will adapt the New GM automatics 6L80E or 6L90E 4WD to either GM & Dodge NP205 Figure 8 bolt pattern NP205's. Kit 50-9551A, 6L90E adapter assembly includes new female 29 spline NP205 input gear and shaft, NP205 adapter ring, 6L90E conversion tail housing, input shaft bearing and fastening hardware.

Kit 50-9551B, 6L80E adapter assembly includes new 32 spline female NP205 input shaft, NP205 adapter ring, 6L80 conversion tail housing, input shaft bearing and fastening hardware

Transfer Case

The kit is designed for GM NP205 figure 8 front bolt pattern NP205 10, 27 or 32 splines and Dodge NP205 figure 8 bolt pattern 23 & 29 spline NP205 transfer case. Please note that there is no machine work needed on the GM & Dodge NP205 with big bearing bore cases (29 & 32 spline inputs). Note: Small bearing bore case Dodge 23 spline & GM 10, 27 spline NP205 transfer cases will need the front input bearing bore machined to big bore specifications.

Transmission

GM's new Hydra-Matic 6L80 & 6L90 transmissions are the first of a new family of modular six-speed rear-drive transmissions. The transmissions feature two overdrive gears and a wide, 6.04:1 gear ratio spread to improve performance and fuel economy when compared with conventional four- and five-speed automatic transmissions. With two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph - a reduction to about 1,500 rpm. Lower engine rpm can bolster fuel economy because less fuel is used. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle's cabin.