I'm not too sure how much different they are? somebody else on here might know. I think the bore size of an L28 is similar to an RB26. As for pin size, pin to crown height, etc I wouldn't have a clue. One of my sponsors has kindly agreed to pay for the pistons and isn't too concerned about price. Time is the only problem because the next round of the series is mid October and I need them here in time to get the engine built and run in!