Thanks for the quick reply
"Be sure to use the 98 ECU".
Will the wiring harness from the '99 Laredo plug directly into the '98 ECU? Do I just unplug the ECU from my '98 and plug directly into the '99?

That's related to my next question which is, Will all the wiring harnesses for things like the transmission, transfer case from the '99 plug/connect to the transmission, transfer case that I am going to put in. Will the linkage in the '99 bolt up to the transmission /transfer case from my '98.
Sorry to be a bit anal on this. Just don't want to have be half way through the job and realize this connector doesn't fit or this rod is to short. I just don't want any surprises