Sorry to keep everyone waiting. I've been lazy the last few weeks. I do have the artwork of a gearset on my dining room table right now. I just need to spend the time installing it. I see no reason why you couldn't replace just the 5th gearset pair. However, as I stated before I've had 3rd and 4th go in the same fashion so it may not be worth the risk. My current final drive ratio of 3.2:1 should net me 150 in 4th and 200 in 5th at 7500 rpm with my planned tire size. Though I'm not sure I'll ever go north of say 170.

Any updates? :)