I just bought an 88 dakota 4x4 from a government agency knowing that there were potential issues with the 4 wheel drive. They taped a note to the 4 wheel drive shift handle that reads ( Do not use 4x4 or parking break, bad things may happen). There seems to be some oil around the front differential and the transfer case seems to be a little damp with oil.
I have not attempted to engage yet. Other than checking oil levels and giving it a shot, does anyone have any advice.

 

Use baby steps. I would check the oil levels and engage the 4x4, when stopped, to see what symptoms you have when you try to drive it. There is no way to trouble shoot things without any symptoms to work with. I do not know of anything catastrophic that can happen just by engaging the 4x4 when stopped and trying to take off. I would not try engaging 4x4 while driving until you get it to work when stopped.

With the parking brake you can pull the rear wheels and drums to at least look at the working parts for anything obvious. I would then try having an assistant engage the parking brake with one drum at a time off, to see what what does or doesn't work.