Chevy Engine codes and such....

[sd-slider]

Wanted to see what some of you have made of the somewhat "cryptic" nature of the 350 Small Block casting #'s and date codes..

I am getting ready to re-power my 69' Step and needed all of the pertinent info for possible trade-in for core. Here are some #'s I pulled off of the block and heads:

Block Casting # - 3970010 (Date code is: D281)

Head Casting # - 3973487 (Date code is: D281..strange?)

Both date codes appear to be April 28, 1971 based on specs that I have found at various sites and publications. I have also seen varying information that says this could be either a 307, 327, or 350.....anyone have any reliable sources for information on this?

What has me wondering is something as simple as spark plugs.....I picked up some new plugs based on the 71' theory to replace the Autolite "145" plugs that were previously installed(not by me..), and they don't fit. Autolites application specs don't even mention compatibility with any 71' 350's...


Any info or links would be greatly appreciated.

=Slider