The only place that the tape is used is on pipe threads and usually not on automotive. I think the exception might be on something like a heater hose valve. I don't own a 46 truck but from the manual, I don't think that hole should be there. I am guessing that the master you have there is for an earlier model. On my 38, there is a port where the pressure switch mounts, and it uses a pipe thread. I would not depend on tape on a pressure fitting like that and I would imagine that the tape would dissolve anyway. Maybe someone will chime in here.
