Hi all, I'm Gerry and needless to say i have a 57' 4104 conversion... :)

[zubzub]

FWIW there is a relay (in the rear electric bay)  between the reverse switch on the dash and the solenoid  on the transmission.  In my case the relay was intermittent, leading to 2  rebuilds of the solenoid til I figured that out.  The relays in general are old and fussy at this point and are worth changing out as you go.