[Boatanchors] Azden PCS-4000 tone unit instruction needed

[HL1FB]

I own an old PCS-4000 2m trx and I built a simple 88.5Hz tone unit to install into the radio.
I found a space for a tone unit inside the radio but I could not figure out how to wire
the tone unit.
Does someone have an instruction sheet to install a tone unit into PCS series radio?
I already have a schematic for the radio.
Thank you in advance.
de HL1FB/WW6N