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NV4500 Retrofit Kit - Replacing TH400 in GM Full Size (1979 - 1985)

Your Price: $900.77
Retail Price:$917.34
Your Savings:$16.57(2%)
Part Number:AA-27-0032

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Advance Adapters


No. Qty Part No. Description

1. 1 Kit 50-0206 4WD NV4500 TO GM NP205 32T

2. 1 Kit 712576 NV4500-1996 GM BHSG ADAPT. KIT


4. 1 Kit 716050C NV4500 SHIFT HANDLE ASSY.


If you’re attempting to build an unbreakable drivetrain, then the ultimate connection of a GM 4WD NV4500 to a 1971-85 NP205 (replacing the SM465 or TH350) must be considered. The adapter was engineered for heavy-duty truck applications. This installation uses the largest spline size available (the factory 32 spline GM NV4500 output shaft), and offers the maximum strength of any of the NP205 conversions. The kit requires the purchase and installation of a new 32 spline input gear and bearing (Part No. 716038). The new input bearing is approximately 1/4" larger in diameter than the stock bearing. Some machining on the transfer case is required in order to accept the larger bearing and new input gear.

This kit also is designed for the 1979 to 1985 1-ton truck with a TH400 transmission. This particular transfer case is already equipped with the proper input gear and bearing, so no machining is required.

The kit utilizes the stock 32 spline GM 4WD NV4500 output shaft. This shaft must be shortened to a stickout length of 7.625". With the output shaft shortened and the adapters installed, you will find the assembled length to be approximately 19-1/4". The new adapter uses a seal in the adapter housing and a sealed bearing in the transfer case, which is required to isolate the different fluids. The transfer case adapter kit uses two castings to couple the NV4500 to the NP205. These castings have been machined to allow for proper transfer case shift rail clearance. A shifter bracket has been provided to mount the stock NP205 shifter handle; however; you may be required to modify the handle to properly fit up into the cab of the truck.

The bellhousing in this kit bolts directly to the front of the NV4500. Since this kit was developed primarily for vehicles originally equipped with the TH400 automatic transmission, we’ve supplied a slave cylinder bracket for your clutch linkage (P/N 715535). This bracket is designed to fit 1985-1991 GM slave cylinders (GM #15615868). A hydraulic clutch system is much easier to install than a mechanical linkage. If you decide to install a mechanical linkage, you can substitute for bracket PN715534.