Tube ID & Code Help Needed

[Trout]

I aquired an old 60's Lowery organ over the weekend.

Long story short,

I got a quad of 7591's out of it, But I have never seen this particular brand.

The date codes on the 12AX7's are RCA style year/week (65-17)

But The 7591's use a code I am not familar with, Possible Sylvania? I would Like to date these.

See pictures

I have never heard of CMI tubes , perhaps re-labels. They say made it usa.

CMI 7591

CMI 7591 Top View

Thanks
Trout

 

[Trout]

OK, I think I found at least part of the info.
337 Is the manufacture " Westinghouse"

So I assume the lower numbers are date?

526?, I know for sure the unit was from the 60's
Trout