The reverb tank is matched to the reverb transformer if that is what you are asking.
I don't know why it would work in a fender and not a marshall. 12AX7's in both preamps. The tube manufacturers set the specs a tube needs to work, not fender or marshall.  If there is an impedance mismatch, I don't know

Thanks again, I have looked at that drawing many times trying to solve this problem. This drawing is newer then the circuit that I have, and uses transistors, diodes, and/or optoisolaters that "I will not use" ! I am not looking for HI LO input switching. The LOW input has been removed. The circuit is hardwired so that C3 R5 C4 join, bypassing J2 and keeping 4 gain stages with the tone stack at the end of the circuit as it would be if you just plugged into the HI input.

I am starting to think that I am going to change the circuit to an older 2204, tap the reverb input before C9 and use the low input J2 for the reverb return instead of bringing it back in at C9

Thanks for the response, but  what is ppimv ?  I have already tried to tap after the treble , and after the master volume as well as several other locations and the only place that somewhat worked is where I stated I am using. I even tried a 2.2k and 270 ohm resistor on the feedback circuit like fender does for a line out as the input to the reverb. all it does is ocillate where ever I try. I think maybe it has something to do with having 4 gain stages , but as you can see, I am not an expert. Posting here is what I did after all else failed. I will try tapping around C9 and see what happens.

As far as the rest of your comments go, all I can say is
 
Just looking for something that nobody else I know has.
Different strokes for different folks!

Thanks Again

Hi, I am an experienced amp tech. I am trying to add reverb to a 4104
I have installed the reverb transformer and 2 9pin sockets to the chassis
I'm using a typical black face fender reverb circuit.
I am having trouble finding where to tap into the preamp for the reverb input.

When using only the HI input(J1) on the 2204 circuit
I am using the point where C3 J2 R5 C4 join for the reverb input
and point "Y" (input to the phase inverter)
to bring the reverb output back into the circuit.

The reverb works, but the tone stack does not. When I take the reverb out of
the circuit the tone works again so I know this is not right.

Any Ideas ?