If its still got 2 HO tubes the FBT is original. The G13 & H12
had a massive FBT kit with tons of mods. If you knew one was in
line to do you called in sick & stayed home sucking down
Schlitz !
BTW if it has a 6EW6 vid amp change it ever few yrs. They get
weak & the details get lost, looks cartoonish. A fresh one brings
back things like hair, freckles etc.
73 Zeno
LFOD !