I have been looking at the schematic of the U67, but on the schematics I have seen, it is not marked which pin (4 or 5) of the EF86 is connected to ground and which pin has the (negative) filament voltage.
Of course for a indirect heated tube this is of no importance, but I would like to experiment with a solid-state equivalent of the EF86.
So, more information is welcome!
(Reasons for this experiment: no ageing, no microphonics, low(er) noise, long life.
I have used the Phaedrus VF14 and AC701 solid state replacements with success in the past.)