Need help with 289 block ID

[ohio5.0]

Hey all. I recently picked up a really clean low mileage 65 coupe with a 289. I'm pulling the motor to freshen it up. The block has 7D18 and C5AE-6015E on it. The heads have 289 and 66 on them. I think this indicates it is a 67 block with 66 heads. The prior owner said he thought it had the original drivetrain but wasn't positive. Anyone out there that can help? I'm throwing a 302 in it for now and was planning to rebuild the 289 over the Winter. If its not the original block then its not that important to get this one back in it to me.

[draggin50]

C=196X
5=1965
A=Galaxy
E=Engine

Date code of the block 7D18 means April 18, 1967. This is more accurate than the C5AE. It is possible that it is matching numbers engine.

http://www.fastbackstack.com/2007/06/how-to-decode-your-1965-1970-mustang-engine-block-number/

Your heads should also have a stamping like the C5AE as well.

[ohio5.0]

Thanks for the info. That confirms what I thought. The date code means it most likely isn't the original block. I also see signs it was blue before someone sprayed it black. From what I can find 65 blocks were supposed to be black.