This Advance Adapters TH400 to NP205 adapter kit is designed to mate a GM TH400 4WD automatic transmission (with 2.5-inch output shaft stickout) to a GM NP205 gear-driven transfer case. This kit is intended for applications where a SM465 4-speed manual or TH350 automatic transmission is being replaced with a TH400.
It provides a complete solution for converting to the stronger TH400 while retaining the legendary strength and reliability of the NP205 transfer case.
NP205 Transfer Case Compatibility
The GM NP205 is a part-time, cast-iron transfer case featuring the classic Figure-8 front bolt pattern and was widely used in GM trucks from the 1970s and early 1980s.
NP205 units originally paired with a TH350 automatic use a 27-spline male input (1971–1979)
NP205 units originally paired with an SM465 manual transmission use a 10-spline male input (1971–1984)
This adapter kit includes a new NP205 long input gear with 32 internal splines, allowing proper engagement with the TH400 output shaft.
Note: The NP205 transfer case must be machined to accept the larger diameter input bearing included in this kit.
Transmission Compatibility – GM TH400
This kit is designed exclusively for GM TH400 4WD transmissions with a 2.5-inch output shaft stickout. The TH400 is a heavy-duty automatic transmission with a 24.250-inch case length and the distinctive “Texas-shaped” oil pan.
TH400 output shaft spline count: 32 spline
Compatible only with 2.5" stickout TH400 output shafts
Not compatible with TH400 transmissions using 1.5" stickout output shafts
Always verify transmission output shaft length before ordering.
Kit Contents (Bill of Materials)
- Adapter – TH400 to NP205 (51-3202)
- NP205 Long Input Gear, 32-spline (52-9600)
- GM TH400 / 4L80E Gasket (716510)
- NP205 Adapter Gasket (716572)
- Input Gear Bearing – 6210NR (716320)
- Adapter Seal – National 4435 (716754)
- Snap Rings (716467, 340407)
- Brake Yoke
- Linkage Rod and Bracket
- Soft Plug
- Complete mounting hardware set
- Installation instructions
Ideal Applications
- TH400 upgrades in GM 4WD trucks
- Replacing SM465 or TH350 transmissions
- Heavy-duty off-road, towing, and work-truck builds
- Restoring or upgrading NP205 transfer case drivetrains
This adapter kit delivers a durable, proven solution for combining the strength of the TH400 automatic transmission with the unmatched reliability of the NP205 gear-driven transfer case.
Bill Of Materials
