my 4 4 doesnt work on 91 v8. I found a vacum line unplugged right under the carb but cant find were it goes. Can that be the problem?

 

It might be, but I doubt it, check the shift linkage, I find the linkage out of sync on these all the time

 

I think most likely that lose hose is your problem. The cental axle disconnect uses engine vacuum to engage the axle. So if no vacuum no 4x4. There should be a round looking setup on the axle and that is where it should plug into. See the pic. It is the sideways yoyo looking thing with the white conector on top.