All the engines were assembled at Tonawanda. Valve covers and intakes were installed and for the L72 engines after adjusting the solid lifters, chrome valve covers were installed. The date and suffixes were stamped at this time. The engines were then put on shelves to be shipped as needed. My May 1968 439 casting was pulled on December 1968 to be installed into My 69 SS427 L72 Impala. At that time the Vin number was supposed to be stamped onto the block. They were in such a hurry that they never stamped mine. They never even stamped My POP with the engine code. The window sticker was printed with the information, and the dealer invoice. My car was shipped on the 3rd week of December 1968. I prepped it on 4th week, and filled out dealer prep. I drove it home December 24, 1968in a blinding snow storm with H-70-15 snow tires on the back. Marc. What date do You have on Your engine? NICK L72