91 4.0 into 89 2.9

[MichiganLarry]

I have read most of the swap articles on this board about this swap. I found a 91 ranger with a 4.0 that I can get for cheap money to swap for the tired 2.9 in my sons truck. Since they are both gen 1 trucks would this be a plug and play swap? The 89 has a CEL.

Thanks for your input.