A little more transfer case help

Thanks to everyone who responded and answerd questions about installing a YJ 231 into my XJ. I have one more question. After removing my old case I noticed one difference besides the shift lever needing to be swaped. there are two elec. plugs on my original, and only one on the new one. In place of one plug that has two prongs is what looks like a vacuum plug with 4 ports . W hat does this do. Was it for a axle disconnect? Do I need to change it and if so , how?
SASS

The vacuum connector was for the disconnect front axle found on early model XJ's. I'm running a transfer case with the vacuum attachment but do not have it connected. The case will work just fine but I'd reccommend plugging the inlets just to keep contaminatin out.