Thanks for the info ..
I guess I was looking at the wrong end of the code .
Here is the deal LOL
Helped a guy put this motor into a chev pickup a few years back .
He took it out of a write off pickup :??
Was told it was a rebuilt 327 .
Now the harmonic pulley came loose and ruined the crank .
There was no center bolt in the crank. or no hole with threads to put a bolt.
It was pressed on I guess ::????..
Anyway the motor has two different heads .
One is 3986336 .. and the other is 3932441 .
I want to rebuild this motor..
I have a set of 3991492 chevy heads to go it ;so at least the heads will match .
If I put the smaller heads on this will my horse power go up much