The Output Spacer for 700 Transmission locks out the location of the internal gears. 

This will allow you to remove gears in your 5-speed to make it a 4 or 3-speed transmission. This helps reduce parasitic loss made by the addition gears. It also has built-in stops to keep the shifter from going past the last available gear. It must be used in conjunction with the 786071 Countershaft shaft Spacer.