it is a long rod 4mm wiseco crank. On the rz forum they gave me the rod length of the rd 400 ( 5.810" small to large end) and thats it on the nose.I have a new wiseco long rod 4mm crank and it matches in all dimensions.I think the previous guy didnt want to use the wiseco 795 pistons since they cost so much so he used standard ones and recessed the head and put in a thicker base plate to compensate. that sound right ? unfortunately my builder bored the cylinders to match a set of standard wisecos and as long as this combo works ill redo it that way, though long rod special pistons,standard base plate and head would probably be better. used this builder since hes local, i had what i thought were the correct parts and i didnt think i would find this mess when i cracked the head !