Engine 99 P71 Engine And Computer Installing In A 96 Gt, Start Help

Please explain WHY you are trying to transplant a PCM from a 99 Crown Vic into a Mustang?

Are you changing transmission type (automatic/manual)? What's wrong with the transmission in the Mustang?

The 99 CV has the SAME non-PI Romeo motor that came in the 96. Why not just transplant the wiring harness, fuel injectors, induction, EGR, oil pan, Front ACC from your Mustang to the new motor? In sort, dress the new motor to look like the Mustang's motor.

Remember that the flywheel/flexplate will need to be matched to the type of transmission used (auto/manual).

As a reminder that the automatic transmission from a 99 is NOT a plug and play transplant into a 96. For starters, the speed sensor is different (OSS vs VSS). The DTR is pointing the wrong way and likely the tail shaft is different.

If the new motor has an external oil cooler then REMOVE it. Transplant the oil filter adapter from the Mustang to the new motor.

This will save you a TON of work. Besides the fact that the CV PCM and wiring harness won't work in a Mustang.

Police duty motors spend much of their life idling. Hope you didn't over pay. If this were my project, I would also pull the front timing cover and inspect the chains and tensioner before re-installing this motor.