I'm not sure this is the right place to post this or not, but here's my question. I may have found a 425 for my project but the guy says the engine ID is W399 / 6C12064. That doesn't seem right to me. I thought the 401 and the 425 had an engine code that has an MT in it. I have had no luck figuring this out. Can someone help me out with this before I make an 8 hour drive for nothing. Justin
Justin-with the w399 digit on the passenger side of the thermostate housing is the engine code-yes MT for a '66 401 and MW for a standard 425. The other number you show is the VIN on the driver's side-and it's a Calif car-have the seller look harder- also a '66 425 was red-good luck
