Dynamic Racing Transmissions has developed a kit to replace the stock Number 9 thrust washer, located under the rear sprag, with a unitized needle roller bearing.
Anytime you can reduce friction, you are freeing up power. And adding rollerization in place of a fixed surface is the way to go.
The Dynamic kit requires disassembly of the unit for install, but is a simple swap of the existing components.
Kit includes 1) Modified inner race and 1) Needle roller assembly.
Full instructions included.