I just done a swap from a 24 valve to a 12 valve motor and I would have to say it's essayer than a p-pump mod on a 24 valve. The only things I had to buy was a 98 PCM and a 98 Wiring harness, 98 Throttle cable and a oil pressure sending unit. The truck started off being a 1999 1 ton Dually 4x4 auto 24 valve. I started by buying a harness for 150.00 and then the pcm for 160.00 they came from a auto 98 4x4 12 valve truck. Everything bolted right up plugged right in and it's now a 1999 1 ton 4x4 12 valve manual truck ( 12 valve, NV5600 6 speed, 271 T-Case ) It was easy wiring up the fuel shut off solenoid too and was all done inside of the PDC. I have to say if you thinking about it just do it, it easy! It looks stock all wiring, hoses, exhaust, and yes all my gauges work with no splicing!! Money into doing this - motor is around 480 to 500
