Did the brakes on an 84 here, and found that AllBalls kit as you say. The front ones though have both sides in the one kit. For the rubber flat cut o-rings I could not find anybody who made them or the size, so I went to a local brake rebuilder and he said just to use normal o-rings, at least that is what he would do and he said it would work just fine, so that is what I did. Now the manual says not to slit the caliper, I wonder why?