Can I fit a 3.0 V6 into my 86 2.9l or will it be to much work

 

One of the mounts is identical (Same part number), on the other side the part number differs, but mounting points seem to be the same.

So in short answer, yes.

Though given a 4x4 and the chance with a lighter chassis, like the 89, why not a 4.0?