Can anyone help me decode the serial numbers off of a motor? The number is 5H315384, it is in a '66 buick special. Thanks in advance for any help you may be able to offer.

I think that is the engine serial #. It only tells us that the engine was made in 65 in Flint. The last 6 digits match the vin of the original car where the engine started. Keep looking for a two letter code that will give us the production code. Here is a link to the production codes for various years and engines: http://www.buicks.net/shop/engine_ident.html . Scroll down to 1965, and match it up to what you find on your engine. Good Luck!

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Steve B.
GSCA #2173 (1986)
67 GS 525 Stg IV
66 GS Convertible
65 GS HT
63 Riv