Wire connections for a S10 front diff swap

[Roadstar01]

I recently installed and wired in a NP246 Transfer Case from a 2002 Chevy Silverado donor.

I quickly found that the OEM AWD front diff on my 2001 GMC Safari would not allow for smooth turning because the front passenger axle was always active. I went ahead and pulled a front diff from a 2003 Chevy S10. After researching this component I found that it runs off a vacuum actuator to lock in the passenger side axle on command when 4x4 is called for . 

Now I'm in the middle of wiring it in. As you may know the Silverado has a 4-pin connector for the front differential encoder motor which the S10 front diff only has a vacuum diaphragm that pulls the mechanical cable which lands in the differential which actuates a fork pulling the gear and making it active on the right CV axle output. 

I want to use the auto 4x4 push button option that I also pulled from the Silverado and mounted inside the van. I need to connect the two wire electric solenoid that shuts off or allows vacuum from engine intake to enter the front diff diaphragm vacuum line only when the transfer case calls for 4x4. I suspect the transfer case has to go into 4x4 first and then the front diff actuator but unsure if I connect to the transfer case control module or one of the two sources I see in a one-line diagram.  From a one line wiring diagram for the push button panel switch controls I found there are two wires that activate the front encoder motor if it had one that was original on the silverado but the S10 has a two wire solenoid for the remote vacuum actuator.

On the one line wiring diagram, one is called front axle switch signal circuit 1695 and the other is called front axle actuator control circuit 1296. Which one of these if either would I splice into, again I've been told the transfer case needs to go into 4x4 before the front diff I'm sure if this is true or not or how this is affected any help is very much appreciated. The picture is of one of the wiring diagrams and I highlighted the switch signal and actuator control.