Hi,

Just thought I would mention a few things and one is pulling your hair out, doesn’t fix anything and most of us lose it anyway.

Like hair, you are missing a connection. :-)

How do you know you are not charging?
Are you looking at or for an idiot light?
Do you have a voltage meter in the dash or a hand held VOM? A dash meter is highly recommended.

On all 5 of my 6 240’s have a dash meter and the one has a digital one with a battery drain warning piezoelectric tone. So I don’t leave the lights on. I Got it in 1979 for that second reason as a plus factor.
Now they use a non thinker relay system for those other idiots like me.

The alternator’s housing needs to be grounded by it’s own wire to the engine block.
The engine block gets its own ground on the other side directly back to the battery.
I’m not familiar with the mounting location of a 745’s alternator but the principles are the same on all alternators.
The voltage regulator looks for a potential difference between the housing ground and the systems voltage on the B+ wire. It’s made to hold a set difference.
B+ Is the big wire coming from the battery VIA the starter motor.
If that connection, over there, is loose or missing you will get nothing.

Now there is one more wire that comes from that instrument cluster and it is call a D+ wire.
It applies a small current to and through the regulator to ground. This excites the windings in the alternator to start an output. From there it’s self regulating of the B+ wire.
No input on the D+’s wire the alternator does not put out anything.
When that happens the light stays on.
If you have no light at ALL, then the wire is not connecting or there’s no ground.

Disclaimer: The following is not recommended unless you are in a desperate last resort dilemma.
This bypasses the current limiter built into the cluster.
If you jumper, by flickering or temporarily holding a connection, from the B+ to the the D+ Connection.
The alternator will then give out an output if the alternators housing is grounded correctly.

Recheck all your wiring since you had the engine out of the car. That’s a hard way to change a red blocks seals. IMHO.

GOOD LUCK

PHIL