3970014 rear casting number says 350-70 to 76 (mortec)

Front pad stamp is T0929CMJ

Thanks in advance guys:)

Also, regardless of what it came out of, is this block worth keeping?

~Dan

I think this may be right

T0929CMJ

T - is the assembley plant (Tondawanda)
09 - Month it was made
29 - The day of the month
CMG - Suffix, which my book only goes up to 1969 but it is intended for the application for that engine and the model year it was built.

From Alan Colvin's book "Chevrolet by the Numbers":

"Block #3970014

This could be considered a mystery block. There is no Chevrolet documentation from the Flint Michigan Engine Plant to show that this block was ever built. There were 5 separate engine plants producing blocks during the 1972 model year. It is possible that one of the 4 remaining plants produced the block. There is also documentation published which points to the possibility that some late 1972 Corvettes came with this block, but this is also unverified to date. Tonawanda Engine Plant records indicate that there were no complete engines built with this casting number at the Tonawanda Engine Plant. However, there was a Tonawanda metal casting plant where these blocks were cast in 1972."

So, I guess it's your call :confused:

CMJ is a 1975 350-145 HP RPO L65, 2-bbl carbed hooked to a TH350 trans and used in Chevelle and Impala models.

That stuff of Colvin is a joke it would seem. This block was cast at Tonawanda. 3970014 saw widespread applications in every Chevrolet model in both 2 and 4 bolt main bearing design, it was used from 1969 to 1979, millions made. Every casting book I look in shows this block.

Thanks Guys;) always come through with a wealth of quick info, cheers.

I get basically the same as El Camino. Good engine to make a 383 if it's a 4 bolt.