I got 3rd gen ruf on 2 rigs, Ive done numerous sas, all with ruf, basically, ive used all yr ruf in all types of builds.
If you are starting from scratch, 3rd gen RUF are the best, they will have the best ride, and the most flex.
The way h8pvmnt has his shackles CAN make it taller, but if you notice, it allows him to run a super short shackle, which pretty much puts his rear spring eye where it would be with a tube through frame shackle. So there is pretty much 0 difference there, besides looks. I personally do it through the frame.
Ive noticed that 3rd gen do not move the axle as far forward as 2nd gen ruf, the pin is in a dif spot. The spring is longer, but a 2nd gen set will push it farther forward if bolted into the same spot. They do not lift it much, like any other ruf, you get all your lift from how you build your pack. I like a super pushed forward axle, no drop hangers, and enough lift to have usably uptravel so it doesnt ride like
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This is mine now