I believe the TH 350 was first used in 65 or 66, so it's possible you've got an original setup there. I've seen some "Target Master" crate engines with the number like you're describing on the front pad- - - -no regular alpha numeric ID numbers. Those were new, not reman engines sold by GM dealer parts departments. 283's and some 327's had several ID symbols cast into the end of the cylinder heads. The most common one is a rectangle shape with a pointed center, the "power Pack" head that raised the compression of the 283 engines. A rectangle shape without a pyramid in the middle is the older low compression 265/283 head
Jerry

Last edited by Hotrod Lincoln; 03/30/2014 1:56 PM.
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