ID this tube for me.

[schmee]

It's a 'Silvertone' set, 6L6GC rebrand. Halo getter, grey plate.
I think maybe RCA grey plates... I dont have any RCA's left to compare.

 

[uriah1]

Silver tone used both GE and RCA

Usually the GE I have seen had the dots under tube type

Here are some examples rca

1964 RCA Silvertone 1484 Amplifier Black Plates 6L6GC Tubes Pair | Reverb

Here’s a pair Silvertone branded RCA 6L6GC output tubes from a 1964 Silvertone model 1484 Twin Twelve in exceptional condition. Ridiculously low hours on both. Both show a 1964 date code with the RCA mfg. code. Highly desirable black plates inside the glass. Perfect for restoring your prized Silv...

reverb.com

 

[SnidelyWhiplash]

Does it have any EIA codes/#s on the base?

 

[rdjones]

Sylvania

GE would have the dot pattern, and RCA usually have side getter,
I've got a Sylvania here that's very similar in construction.
Very good tubes.

 

[schmee]

I sold a bunch of tubes in 2021 so don't have many comparable's anymore. I do have WGB sets but they are different.

Some RCA would have the 'stop sign' around the numbers...although IIRC not all years did.
GE has dots under the numbers.
I have one Sylvania 6L6GC here but it has a side halo getter.

Unfortunately they dont match bias very well in the amp. I have three sets of WGB's that match within 1-2 ma.
It appears they are RCA Grey Plates:

Vintage RCA 6L6GC USA Made Matched Duet of Vacuum Tubes Used & Strong Tested | eBay

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