TH400 to Dana 300 - 1.25" thick

Benchmark Adapter

Kit Components

Kit #10-1004 -- $450.00

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NOTES:

  • ADAPTER THICKNESS - 1.25" BILLET ALUMINUM
  • INCLUDES NEW 32 SPLINE INPUT GEAR FOR THE DANA 300
  • AVAILABLE WITH ROTATION RING (SEE KIT #10-1010)
  • PROVIDES STANDARD CLOCKING OF THE DANA 300
  • UTILIZES STOCK GM 4X4 SHORT OUTPUT SHAFT
  • DOES NOT USE SEALED BEARINGS OR SPUD SHAFTS
  • GRADE 8 - 12 POINT BOLTS ARE SUPPLIED IN THIS KIT

Features which set our adapter apart from others are reflected in the quality of the machine work exhibited in the kit components. The adapter plate is machined from a solid block of T6061 aluminum and measures a short 1.25" thick. Typical adapters for this application will measure nearly 4" long. This adapter does not "clock" the Dana 300 higher than stock (For rotated positioning, refer to adapter kit #10-1010).

Benchmark Adapter

Example: installed unit

The use of this adapter kit requires the TH400 to be equipped with the short GM 4x4 output shaft. This short output shaft can be found in NP203/TH400 applications.

Benchmark Adapter

Output shafts - GM Short shown far left

The kit includes a new 32 spline input gear for the Dana 300. Most adapter kits on the market utilize stock GM 2WD shafts which are cut down in size and resplined to match the smaller 23 spline input found in the stock Dana 300. Unlike these other adapter kits, our adapter kit retains the high strength offered by the 32 spline GM shaft.

Benchmark Adapter

Dana 300 32-spline input gear

Spline Engagement:

Our adapters are designed to be short in length however we do not sacrifice spline engagement in any case. As mentioned, this adapter kit is designed to be used with the short style output shaft (32 spline) found in the 4x4 TH400. JB Conversions, Inc. can provide this GM shaft if you do not have one. Notice the fully engaged spline in the photo below. We have seen some varients in the GM short output shaft length. Therefore the shaft may need to be shortened slightly with a cutoff tool.

Benchmark Adapter

Spline engagement

Driveshaft Clearance:

Driveshaft considerations must be given to the use of any Dana 300 mounted behind a TH400. Typical driveshaft diameters for the rear of a Jeep will measure 2" OD. In applications such as this, front driveshafts should be smaller in outside diameter and heavier in wall thickness.

The photos below show a 1.25" diameter driveshaft horizontal with the oil pan of the TH400. The driveshaft does not touch the pan in this instance. In review of this adapter for your application, be sure to consider the full range of your suspension travel and the location of your front differential yoke. Adapter kit #10-1010 offers better driveshaft clearance, however costs are higher due to additional kit components.

Benchmark Adapter

Photo of front driveshaft