Who manufactured this upper?

[4b1t]

Have had this upper for about 15 years. Curious as to the quality/manufacturer. Markings as per the pics below.
Fluted barrel about 10.5 ". Barrel diameter as follows: Chamber 0.980", main portion under HGs 0.950", behind FSB 0.850", at FSB 0.750" and forward of FSB 0.720".

Any info appreciated.

 

[Power Pill]

Diemaco / Kaiser Aluminum


http://www.biggerhammer.net/ar15/uppers/

 

[rambones]

interesting upper, any writing on the barrel?