I recently took delivery of 2 used but in excellent condition front rotors from a 1991 K75 to replace the very rusted ones on my as-is purchased 1992 K75S. The seller assured me that the 91 and 92 rotors were the same but in looking at them side- by- side there are a couple of visual differences. On my 92 the discs are secured to the mounting plate with bolts; the 91 uses rivets. Also, the 1991 rotors are a couple of thousaths of an inch thinner. Before I pull off the front wheel can anyone tell me if they are interchangeabl or provide any other info that could be helpful? Thanks