Gen4 and Gen5 rear wheels are the same, rotors are different shape but the OD is the same so in effect the rear wheels are interchangeable between both gens.
Fronts rotors are not the same at all. Gen5 is 330 OD and Gen4 is 310. Moreover, Gen5 RR is 330 OD but the carrier is dished (because of Marchesini rims) while R is 330 but carrier is flat.
I overlooked this but thanks for the info! Exactly what I was trying to figure out!
Do you know anyone else that makes a spacer kit for front wheel (gen4 to gen5)? OP is no longer making them... Certainly a cheaper route finding gen 4 wheels! I paid less than half of what a gen 5 rear complete is going for!