Help identifying Sylvania tube.

Highvswr

A friend tossed me a couple old tubes; one being a JAN 5Y3WGTA in the box (very tattered). The other I have not had any luck identifying on the internet. The tube is the size of a 12AX7, horizontally marked ( in green)
ACL
SYLVANIA
Made In USA
And marked vertically.
552
These are the only markings on the tube I can find. I have a pic but appears to large to upload.
Any ideas and why so hard to find?
Thanks

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