OBD1 PCM interchange/compatibility, 5.2 vs 5.9

Something else to be aware of (in case you didn't already know) is that the fuel system is different.

The Dakota would have a return style fuel system with a varying fuel pressure due to the regulator and vacuum connection on the fuel rail. When the 5.9 came out, they changed the fuel system to a returnless style and put the FPR on the pump at the tank, so the fuel pressure is a constant reading instead of varying and might even be a different base pressure. So far, I haven't found a 5.9 PCM that would run a return style fuel system so I think there is no option to run a 5.9 PCM with the stock Dakota fuel system.

The simple fix is to use the 5.2 fuel rail from the Dakota and don't connect the vacuum plug on the FPR. But that might still require upping the pressure some if it doesn't meet the spec.

As I have planned for this, I have had several people tell me that the 5.9 runs fine on a 5.2 PCM, so you could try that as well.