I have a 66 Chevelle SS and am trying to find out if the engine is the original one that came with the car. On the trim tag the info is 66-13817, the build date is 12B. First of all is that 2nd week of 65 or 66? Now for the engine....The block date is a307 with casting #3902406. I think that the block is a 67 396 but I just want to be sure. Another problem is the the block must have been decked because on the engine ID pad there are no numbers or suffix code. The heads I believe are correct because they are dated L15, casting #3872702.
Any help would be apprecitated, thanks.....Eric Scharf

2nd week of december 1966. if you ever find the engine id pad, it might be covered over with paint. the number on the block should correspond with the VIN number

I don't have my "#'s book" with me so I can't comment on the cast #'s. But, the build date is dec 65 not 66. By Dec. 66, Chev. was producing 67 models. My car has a build date of 12C.

12B would be 2nd week of Dec 1965.
casting #3902406 shows to be used on 1967 396, 325hp, 350hp, 375hp, 2 & 4 bolt main applications.

------------------
Steve Strasemeier (70SS)

Thanks for the info. You just helped confirm what I thought,The engine is a 67 casting.

Thanks for the info. You just helped confirm what I thought,The engine is a 67 casting.

Thanks for the info. You just helped confirm what I thought,The engine is a 67 casting.