Wire shift lock-out on Davis Unified Ignition marine distributor mercruiser 5.7

[allmorro]

I am replacing the Mallory and coil ignition on a Mercruiser alpha I Gen II 5.7. The engine is actually a crusader 5.7 that was installed in place of the original mercruiser engine. The existing coil has on the (-) terminal two gray wires, the wire to the mallory distributor, and a black wire. I presume the gray are for the tach (why two?). The black goes to the shift cut-out switch. The distributor I am installing is a David Unified Ignition marine HEI unit. It has its coil built into the cap, and has only two wires existing the unit, one for power (to ignition), and one for the tach. So my question... how does one wire the shift cut-out? Could it be wired into the ignition lead, or would that cause a direct short? Why two gray wires? HELP

 

[alldodge]

Here is some instructions
http://classicinlines.com/DUIinstall.asp

 

[allmorro]

Thanks
Useful info... However still don't know what to do with the shift lockout circuit. Apparently the alpha drive needs a momentary interruption of power to shift to neutral. I have figured out that in my old installation was done by momentarily grounding the (-) side of the coil as the lever was shifted to beutral. Would seem that I need to the same with the DUI ignition.., but there are only two wires ( battery) and tach. So.., would grounding the tach stop the spark without damaging the unit? Or would spicing the cut out lead into one of the three wires going to the coil unit work?

 

[allmorro]

Sorry that was a bit incoherent ...
The distributor has a coil unit integral to the cap.
There three external leads (red, brown, green) going from the unit to the cap/coil. Then there is a provision for two leads coming from the cap marked battery and tach.
I assume the red is (+); the brown ground, and the green the negative trigger for the coil. On the oldinstalkation, the gray (tach?) wires, the lead to the distributor, and the wire to the shift cutout switch were all connected to the (-) terminal on the coil. Since the tach and cutout wires were then connected... That is the basis for asking if simply hooking the shift cut out lead to the tach would accomplish the momentary interruption of spark during shifts into neutral???

 

[alldodge]

Found a thread on OSO which they asked DUI and they said to connect the interrupt switch to the negative side of the coil where the tach wire is

Could also contact Performance Distributors at 901-396-5782
http://performancedistributors.com/contact/

 

[allmorro]

Thanks? that is very helpful. There are two leads out.. will use the tach lead. Will let the forum know how it goes.
jsm