RM20, which tube slot is the PI ?

[Crunchtime]

I'm trying to figure out which preamp tube in my RM20 head is the PI position. There are 3 preamp tubes that are in a triangular configuration. As I recall, two of the tubes are towards the rear of the amp and one is towards the front.

I would usually assume the PI is the one furthest from the input jack on amps where the tubes are all in a row. Not sure what to think with this layout.

Thanks

 

[JKD]

Of the two 12ax7s 'in a row' it's the one closest to the EL84 power tubes.