RM250 crankcases

[Katman]

Anyone know what markings I should be looking for on the crankcases to determine if they're a matching pair?

[F5 Dave]

Sometimes there will be some scribing near the main bearing. But I wouldn't get too hung up on it. Japanese machining is good enough that you would be pretty unlucky to suffer any ill effect of a bit of mix & match from the same model. Why, do you have a bucket full of 250 crankcases? Or an old bike that shagged a crank & looking for Holistic reasons for it dying?