Supermatic 6L80E to NP205 Dodge/GM Adapter Package
This adapter kit will adapt the New GM automatics 6L80E or 6L90E 4WD transmission to either GM or Dodge NP205 Figure 8 bolt pattern NP205 transfer cases. This is a drive common customization for those who want to use an automatic transmission while getting the heavy-duty performance of the New Process 205. Advance Adapters has developed a complete 6L80E-NP205 conversion package that will link this GM six-speed transmission to NP205s that came stock with Dodge and GM vehicles. Note you will need a different adapter kit if you want to connect the Chevy 6L80E to a Ford NP205 50-9550.
We offer different kits depending on whether you’re adapting a 6L80E transmission or a 6L90E transmission. Kit 50-9551A is the 6L90E adapter assembly which includes a new female 29-spline NP205 input gear and shaft, an NP205 adapter ring, a 6L90E conversion tail housing, an input shaft bearing and fastening hardware. Kit 50-9551B is the 6L80E adapter assembly which includes a new 32-spline female NP205 input shaft, an NP205 adapter ring, a 6L80 conversion tail housing, an input shaft bearing and fastening hardware.
Dodge/GM NP205 Transfer Case
The transmission to transfer case adapter kit is designed for both GM NP205 figure 8 front bolt pattern NP205 10-, 27- or 32-spline and Dodge NP205 figure 8 bolt pattern 23- or 29-spline NP205 transfer cases. Please note that no machine work is needed on the GM and Dodge NP205 with big bearing bore cases (29 and 32 spline inputs). However, the small bearing bore case Dodge 23-spline and GM 10/27-spline NP205 transfer cases will need the front input bearing bore machined to big bore specifications.
GM 6L80E/6L90E Transmission
GM's Hydra-Matic 6L80 and 6L90 transmissions —also known as the Supermatic 6L80E and 6L90E — were 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 nine 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 in the vehicle's cabin.
The 6L80E gear ratio includes a 4:02:1 first gear for launching and a 0.67:1 top gear for highway driving. When paired with the NP205’s 1.96:1 low-range and 1:1 high-range gearing, joining them with this adapter kit gives you many options for off-road and on-road performance. The heavy-duty 6L90E transmission is slightly taller and longer, meaning additional mods could be necessary depending on the vehicle. If you have questions about this NP205 to GM 6L80 transmission adapter kit, call the four-wheel drive experts at 800-350-2223.
Bill Of Materials
50-9551B