915 Head casting number / letter

[AZ Steve]

I've read somewhere what the (L) in the casting area means. Possibly production Exhaust valve size? however I don't remember and cant seem to find the information again. I'm looking for a little help. please see the attached pictures.

Thanks

 

[1968rt]

Casting itself was the same. From what I understand the K casting used 1.6 exhaust valves and the L used 1.74 exhaust valves. Would make sense and agree with the vin letter K was the 350 horse motor and L was the 375 HP. Also I think the L castings have a large HP on the alternator boss or a small HP under the intake runner. A throat cut on the exhaust would equal things

 

[66Satellite47]

Interesting, never paid attention to that casting number. I'd just measure the exhaust diameter.