Performance Goodies
The input shaft is upgraded from a “necked down” 23 spline shaft to the Ultimate proprietary billet steel input shaft—which is a larger, custom 35-spline two-piece design that requires a custom torque converter and was found to be stronger than the one-piece design.
The Intermediate shaft is also replaced with a larger billet shaft. The stock 23-spline tail shaft is improved to a proprietary billet 29-spline shaft that increases strength by 20 percent plus over a 23-spline billet shaft.
This modification requires the input shaft on the transfer case to be enlarged to a 29-spline shaft, the same input shaft that is used on manual transmissions.
The larger 29-spline input shaft is used with standard transmissions. The stock shafts are on the left. It’s easy to see the difference in diameter of the shafts, which are significantly increased with the 29-spline Ultimate input shafts.
The planetary gear housings that get used are fully-welded instead of the spot/tack welded style that are used in stock transmissions