Re: front axle disconnect ?
Vac disconnect hubs means there is a vac operated motor, like an electrical solonoid (see '94-'01 Dodge 1500), on the axle tube that activates the hub on that side. You should have manually actuated hubs, which is the preferred style for a locker/limited-slip in the front.
If the S-10 had vac hubs, then you need to find the vac feed line from the t-case and plug it. Look in the library reference section for factory service manuals for those two trucks, or a tranny rebuild shop in your town. (You wanna look in Techtran manuals for the Jeep and Chevy.)