Philips 8580 useful anywhere?

[Avanti]

I have a few Philips 8580 tubes but don't know where they might be used. I can't find specs for them anywhere I have looked, and suspect they are for a guitar amp, but can they be substituted in an audio application somehow? Thanks for any help!

 

[HollowState]

This tube is not well suited for audio amp use, although they might be forced into it somehow. It's a dual tetrode with an instant heating filament (1.1v) originally used as mobile RF transmitter finals.

 

[Avanti]

Thanks for the quick reply! The question now is: where did I get these from? I will investigate further into the guitar amp world...