Green wire goes to coil positive
Red wire goes to coil negative
Brown wire goes to engine ground
Does this sound accurate?
No, it is not!
Plus, this is a Mallory, so you need to look at Mallory's schematic!
The schematic will give you two options for powering the distributor's sensor unit.
One with resisted current.... one not resisted!
While this is the YLU...... (photo eye), the connection is schematically the same.
Note the power being full 12 v here.
As a side note..... if you have counter rotating engines, you'll need one YLM 624
BV for your RH Reverse Rotation engine.
As a side note #2..... before beginning the process, it's best to bring each engine over to #1 cylinder TDC C/S......
C/S being critical here.... and stop at approximately 6* BTDC.
When you install the new distributors, aim the rotor towards #1 cylinder (although there is NO rule that dictates this).
Wire the cap according to firing order.
When wired up and ready to set BASE advance, pull a plug wire and place it into the coil.
Place a spark plug in the wire, and give it a Negative source.... such as the intake manifold.
Caution re; any fuel vapors!
With the Ingition ON, rotate the distributor housing
CCW until you see a spark.
Do this several times to gain a feel and accuracy.
Just when you see a spark, stop and tighten down the hold-down bolt some.
The timing will now be close enough to fire on!
Now set BASE, and be sure to check your TAT.
TAT is much more critical and important than BASE ever will be for a Marine Engine.
See your OEM specs for this.
NOTE: While your new YLM's should offer the correct curve/limit, it is wise to double check this. Excessive TA (and too early) can cause ignition induced detonation..... be careful.
Edit: I saw Mark's Prestolite link, and originally Foo Foo'd it. I had forgotten the Mallory/Prestolite main company connection! Sorry Mark... my bad!
So Mark's PDF file is great, and much easier to read. 
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