I have a 71 RR, and I went with a passion 4 speed OD, and really like. With a big inch high torque motor, it is really nice. You use all factory parts, so it bolts together like factory, and no cutting. That alone makes it a no brainer. No mix matching of parts, if you need something, then just get a factory part. I cruise on the highway around 2500 and between 75 and 80. I think his 4 speeds are readily available.