This is a good question. I myself have one engine that has been around the clock three times still going but?? and one that has only done 76 thousand miles. The later I can not get running after pump being repaired and put back on. this pump is a Boche. now if I wanted I would like to know if the pump from my other engine will fit it as it is a cv rottory. If some one answer you, I will know the answer and can keep my nackard pump engine for spear. cheers Pete