I had a MSD on my donor car, it blew before I could install in engine. Personally I think MSD is junk, JMHO. The word on Opti seems to be a good one will last a long time, a bad one not long. Its just the luck of the draw. Make sure you get a Delco Opti, not a knock off. I actually got mine on Ebay, but it is a Delco. Unfortunatly GM is no loger making new ones so most of the ones sold are rebuilds.