TH400 to NP205 Adapter Kit – GM NP205 Transfer Case Conversion
This TH400 to NP205 adapter kit is designed to mate a GM TH400 4WD automatic transmission (2.5" output stickout) to a GM NP205 transfer case. The kit is intended for use only when replacing an SM465 4-speed manual transmission or a TH350 automatic transmission originally paired with the NP205.
Engineered for strength and reliability, this adapter kit provides all the components required to properly connect the TH400 transmission to the NP205, ensuring correct alignment, torque transfer, and long-term durability in heavy-duty and off-road applications.
NP205 Transfer Case Compatibility
The GM NP205 is a gear-driven, part-time, cast-iron transfer case known for its strength and reliability. This adapter supports the following NP205 configurations:
- NP205 originally coupled to TH350
- 27-spline male input
- Figure-eight front bolt pattern
- Used in 1971–1979 GM vehicles
- NP205 originally coupled to SM465
- 10-spline male input
- Figure-eight front bolt pattern
- Used in 1971–1984 GM vehicles
This kit includes a new NP205 long input gear with 32 internal splines, allowing compatibility with the TH400 output shaft.
Important: The NP205 transfer case must be machined to accept the larger diameter input bearing included in this kit.
TH400 Transmission Requirements
This adapter kit is designed for exclusive use with GM TH400 4WD transmissions featuring a 2.5-inch output shaft stickout.
TH400 transmission details:
- Case length: 24.250 inches
- Output shaft: 32-spline
- Oil pan: Distinctive “Texas-shaped” design
This kit cannot be used with TH400 transmissions that have a 1.5-inch output stickout.
What’s Included in the NP205 Adapter Kit
This complete NP205 adapter kit includes:
- TH400 to NP205 adapter housing
- Linkage rod and bracket
- NP205 long input gear (32 internal spline)
- Input bearing and snap ring
- Brake yoke
- Soft plug
- NP205 gasket and adapter seal
- Fastening hardware
- Installation instructions
All components are precision-machined and designed to work together for a reliable conversion.
Why Choose This NP205 Adapter Kit?
- Designed specifically for GM NP205 transfer cases
- Allows TH400 automatic transmission upgrades
- Ideal when replacing SM465 or TH350 setups
- Gear-driven NP205 strength retained
- Complete kit with no guesswork
- Engineered by Advance Adapters drivetrain specialists
Ideal Applications
- GM truck drivetrain upgrades
- Off-road and heavy-duty 4WD builds
- Transmission swaps retaining the NP205
Bill Of Materials
