I hope you have better luck than I. There wasn't a problem with the parts, they were all top notch. It was a problem with the machine work. Not sure if the machining was done in Mexico however the motor was assembled there. The issue that I was going to have with the dealership that I bought my motor from was that at the end of the year (2009) they were no longer going to be affiliated with GM. It was a GMC, Pontiac dealership that was being dumped by GM. I only had till the end of the year to fix the problem. I was lucky, it wotked out for me. One added note, I have a friend of mine who had bought a ZZ502 that he put in his 70 Nova. He had to take it out and have it re-honed and re-ringed as it was using oil big time. It seems that the honing wasn't done properly and was too coarse for the rings. Another problem with machining.