This matched pair of RCA gray glass 6SL7GT dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas.
Transconductance measured 41/41 for Tube One and 43/43 for Tube Two where minimum (65%) is 32/32.
They have FGS and 3-39 date codes, respectively.
I have played them in my Alan Eaton 45 single ended amplifier and they sound outstanding with Pink Floyd's "Obscured By Clouds." They are dead quiet when the CD player is muted and have excellent frequency response, sound-staging, and dynamics even though this amp calls for 6SN7s.