Need help identifying tube/socket wiring in a homebrew amp.

[AcePepper]

A friend brought me this rewired homebrew amp built in a Fender Pro Jr chassis and cab. No Pro Jr parts remain. Front panel is still input, volume and tone controls. Both power and output trannys have been changed/replaced. The amp has four octal tube sockets. It looks like it's wired for a rectifier tube and two parallel, single-ended 6V6s. It's all true point-to-point wiring. Everything is hung off of tube pins or terminal strips.

The real head scratcher is the preamp tube. The amp doesn't have a tube in this spot, so I'm looking at the octal socket and trying to figure out what tube it's supposed to be wired for. I can see pins 2 and 7 are wired for filaments. Pin 8 seems to be a plate, there is B+ connected to it with some resistors, also a coupling cap that feeds guitar signal to the two power tubes. Pins 1, 3, and 5 are tied together and grounded. Pin 4 seems to be the input, or grid. Pin 6 seems to be connected to the B+ supply through a little sliver mica cap. Can anybody tell me what octal preamp tube this socket may be wired for?

[madkatb]

6sj7 with cathode and g3 grounded for grid leak bias. May not be that tube but the pinout fits and it's a typically used preamp pentode in older amps. Look at the Fender Champ 5C1 schematic.

[AcePepper]

Thanks man! That drawing does look like what I'm seeing in the amp. Now to track down a 6sj7, see what this sucker sounds like.