Model 20 T/C Lower Gear Ratio

  The first step is to acquire the full set of gears from the Dana 18 transfer case. This must be the series with the 29 tooth top gear and 1 1/4" idler shaft. Then dismantle the Model 20 transfer case and replace all the gears with the Model 18 gears. The low range gear in the lower end doesn't clear the case so it is necessary to grind the inside of the case for clearance. You will find you are one gear short in the top assembly. The correct one is not available new. The gear needed is the top gear from the Bronco Model 20 transfer case. It is the top sliding low range spur gear. It has 33 teeth and 15 spline with the Dana number 18-8-58.The low range gear in the top end also doesn't clear the case so it is necessary to grind the inside of the case for clearance.  The end result will be a 2.46 to 1 ratio instead of the stock 2.03 to 1 ratio.

                                                                                                                                                                                                                       

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