I have checked Mortec and Nasty Z28 but I get confusing info. The stamping on the front of the block is F0118YA Flint Jan. 18 YA= C20-35 truck 1968. The casting on the block is 3782870 1962-1968 327 but the date code on back of block is A 11 5 Jan 11 1965. My heads are 3890462 L 1 6 and K 21 6 it has a 2680 crank.The engine is in my 67 Camaro and was thought to be original. Are there any more numbers to check? Thanks Chad

Is your car a Manual Trans?
And are you sure it's a "Y" and not maybe a light or goofy stamped 'M'?
The block and crank castings are common numbers for 1967 327's - again, are you sure of the "A" or could it be a goofy 'K' which, would put the dates right.
Just some info to ponder.

Car is an auto. I went back and checked the numbers again the date code on the rear of the block is A-11-5 the YA on the front is good also.If the YA is correct for a 1968 C20-35 truck the block was cast 3 years before being used.

YA is also a 1965 327-185 HP truck base V8 with 2 bbl carb

Elcamino where did you find that?

Chevy parts book

Just curious had searched everywhere I thought. That fits with the casting date and number. Thanks for the help.