Help! 915 Head I.D. Needed

[Clownbaby]

I have an odd set of 915 heads. Usually their are two main casting numbers on a 60's Mopar head; the model, and the production date. But on this set of heads there is: 2780915 10, and on another area it is stamped 2255. As I understand it, that would mean they were built on February 25th of 65. Consensus is that the 915's were only a 67 head. Anyone have any ideas? There is also a weird looking symbol on the front exterior of the head. It looks like a filled in letter M. Any help is greatly appreciated.

 

[challenger6pak]

Not all 915's are 440. Some are 383 with a smaller exhaust valve. Maybe that is the difference in numbers that you are seeing.

 

[DetMatt1]

The 915s with the bigger valves actually have HP stamped on them as well, or at least one of the sets that I have does.

 

[Chryco Psycho]

Yoyu are not confusing them with the closed chamber small valve 516 head used in 65-67 on the 383 ?

 

[DetMatt1]

My '67 Imperial had the closed chamber 516 heads on its 440 and they were definitely original to it.