Which ECU?

The (mopar chrome) ECU which came on my '68 Barracuda 340 has leaked a semi-hard mollasses like substance.
Assume it is time for new one.
It is a 5 pin unit, but when I looked for one on web only saw 4 pin units.
Will a 4 pin work?
Is the "orange" box the correct one for my motor (stock original 340)?

Thanks in advance for the help.