The blocks casting # is 3955272 '69 396.
The engine code is T1021YQ. I have looked through all of my books and I cant find what intended application the YQ suffix fits. If anyone can help It would be appreciated. My primary concern is figuring out if it is a 2 or 4 bolt main.

The casting code is from a 1969 396, used in all Chevy applications (except Corvette). The blocks were machined in configurations for 265 through 375 horsepower, with both 2 and 4 bolt mains. The easy way to check the mains on an assembled engine is to look at the block just above the oil filter boss. If there are three small holes there, it's a 2 bolt. If there are 2 big (pipe plug) and 1 small (machine screw) hole, it's a 4 bolt.

The YQ code suffix I don't know, it is odd. These engines were generally used until mid '69 (what's the cast date?). It is possible that the engine is a late casting and was used in a '70 car-I've seen stranger things.

Hope this helps.

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T1021YQ decodes as a 1969 396 truck engine, heres the info;

T=Tonawanda NY engine plant
10=10 month=October
21th day
YQ=1969 Truck 396/310hp, TH400, RPO L66, 4bbl carb, series 20 and 30, (3/4 and 1 ton)

Thanks for the help.