So my 318 had a 4 bbl on it when I bought it and I really didn't think much of it, but when I got to looking around I noticed that they pretty much didn't make 318's with a 4 bbl out of the factory (I think there may have been a few cop cars or something with them). So I decided to go pull casting numbers to see what I could find out for the fun of it and to see if I had something off a 273 or a port mismatch from a 340 or 360 intake. The main problem I have is that all the Mopar casting numbers I find are of the format XXXXXXX, but the numbers on my intake are XXXX XX-X with a second number that is five digits. The numbers I have are 2531 15-2 and 03259. When I looked up numbers I saw that there was a 340 4 bbl intake with the casting number 2531915 which is pretty similar in style to my 2531 15-2, but what's the deal? Are my numbers a later style or something? There is a pentastar on the front of the intake as well, so I assume it is a factor Mopar piece as well as the fact that it carries what I assume is probably factory blue paint by the look of it. Any idea why the casting numbers are so different?