transfer Case Gearing - adapter Bearngs - Photo 9021725

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6. With each component ready to go, we started by installing the aluminum adapter bearing. This required us to heat up the aluminum adapter with a torch prior to tapping in the new bearing shown here. The fit was very tight.

Here you can see our completed 203/205 doubler setup. Though not quite as compact as some other low-gear transfer-case arrangements, this unit with its massive helical gears and large input/output shafts can survive under serious abuse and high horsepower.<br /><br />

Here you can see our completed 203/205 doubler setup. Though not quite as compact as some other low-gear transfer-case arrangements, this unit with its massive helical gears and large input/output shafts can survive under serious abuse and high horsepower.<br /><br />

1. The best NP205 transfer case to use for this project is the one found behind the Turbo 400 and SM465 transmissions from '86-and-newer 1-ton GM pickups. If you don't have or can't find a TH400-version 205, Off Road Design has the parts you will need to convert your TH350-version 205 to a TH400 type.

2. This is the complete doubler kit as it was shipped to us by ORD. Our initial inspection of the instruction booklet left us wondering if we should have asked an experienced shop to help out with the installation. However, after familiarizing ourselves with each individual component of the kit, our confidence level increased and we were ready to tackle the project in our home garage.

3. The kit requires the gearbox portion (first 6 inches of the case) of a NP203 transfer case. Luckily, these cases are readily available at just about any domestic wrecking yard in the country. We paid $300 for this used one out of a '70s-era Chevy 3/4-ton pickup. ORD recommends getting a 203 from a '73-'77 pickup equipped with the Turbo 400 automatic transmission. This is preferred because it has the strongest input shaft available (32-spline) on NP203s. For additional transmission/transfer-case configurations, visit ORD's technical Web site.

5. This is how the new input bearing looked once installed after the machine work was completed. We went ahead and rebuilt our NP205 while we had everything apart. You can purchase a similar rebuild kit for around $170.

6. With each component ready to go, we started by installing the aluminum adapter bearing. This required us to heat up the aluminum adapter with a torch prior to tapping in the new bearing shown here. The fit was very tight.

7. Next, we installed the intermediate gear cluster back inside the 205's case. This was followed by both the input and output gear clusters.

8. Then we installed the doubler's low-range gear and output shaft into the input hole of the 203 range box. Once installed, it was time to mate the 203 range box to the doubler adapter. The first step was to apply a good bead of RTV sealant to each side of the adapter gasket. Hint: do one side at a time.

9. This was the hardest part of the installation. The 203 range box gear/shaft assembly requires that several small needle bearings be installed on the interior of the shaft. To do this, we used a healthy portion of thick red bearing grease to help hold each bearing in place. Once all the bearings were installed, the doubler adapter and the 203 range box were mated carefully together.

10. We also installed a thick bead of blue RTV silicone to seal off the PTO access plate on the 203 range box. You will notice there's a port incorporated into this PTO block-off plate-this provision allows you to fill the range box with gear lube.

11. Here, you can see the new adapter plate bolted to the 203 range box. The next step is to mate the 205 to these two. Once connected, we had to use caution while moving this mammoth around because the additional components added a significant amount of weight to the already heavy NP205 transfer case.