have a set of 289 heads c80e 289a 8d25 8b26 one has number 11 next to spark plug the other has number 8 are they hipo heads.

 

Do they have screw-in rocker studs? Of course, somebody could have added screw-in studs later.

The clincher for identifying Hi-Po heads is the valve spring pockets. They are cast into the head, and serve to eliminate valve spring "walk". Here's a pic of Hi-Po heads:

http://mustangandfords.com/techartic...mage_large.jpg

I'm not too sure about that casting number. The 289 Hi-Po was built from '63 to '67, and that's a 1968 casting number...when the 302 was introduced. But I have seen overlap on casting numbers before, so that's not set in stone.

 

thanks alot iwill look into it further.