I'm confident that Gen 5 forks will fit straight up to Gen 4 triple tree, however you would also need either the m50 brakes off the Gen 5 or some other brakes as Gen 5 is 100mm spacing not 108mm like Gen 4, also you would either need a Gen 5 front wheel or the spacer kit one of the forum members was selling as the front wheel is different on the Gen 5. Hope that helps .Will gen5 forks fit gen4 bike?
What other parts Must be gen5?
my understanding is that the cartridge kits for the Gen 4 and Gen 5 are differentLike said above ^^ It's not a direct swap. The rotors are larger on the Gen5, so you would need caliper spacers. The wheel speed sensor is mounted differently, I haven't tried to line them up to see if they end up in the same exact spot or not, they might.
Wasn't something I wanted to risk, I am having my internals removed from the Gen4 and installed in the Gen5.