Can a Harley Davidson 6 speed transmission fit in an Harley Davidson FXR frame?

Yes, a Harley Davidson 6-speed transmission can fit in an FXR frame, but it may require some modifications. The FXR was originally designed for a 5-speed transmission, so adjustments to the mounting points and possibly the swingarm may be needed to accommodate the larger 6-speed unit. Additionally, you'll need to ensure compatibility with the engine and drive system. It's advisable to consult with a professional or experienced builder for the best results.