ISX to X15 swap headache. PLEASE HELP

[Orangecar89]

Ok, so here I am so far with the truck. After a very informative conversation with Rawze, who told me about quickserve and how to pull wiring diagrams and MUCH more, I've made some improvements. Erractic oil pressure and low voltage on 5v sensor circuit number 1 ended up being a damaged Crankcase pressure plug, it was completely ripped out of the harness. Isolated that and the truck is now reading 32 psi at 650 rpm at temp. The shutting down and hard starting ending up being a loose
12volt connection to the ECM, I chased my tail on that one for a while, but when the ECM suddenly stopped communicating with INSITE, it kind of pointed me in that direction. So now, the truck has zero codes that I am able to see with my basic skills and it fires right up and runs well as far as idling and yard driving. My next thing is trying to figure out why I am not reading any RPM on the turbo. I pulled the sensor and I can not find any numbers on it. The truck has a reman turbo, and I believe from the numbers it is an ISX turbo and not a X15 turbo. That being said, I dont know if there is a difference between the two turbos and the two sensors. If the ECM was showing zero rpm, and not setting a code, I am assuming it is being ignored. What would the ECM need the turbo rpm for? FYI, the harness is the original ISX harness with two wires for the turbo speed. Any help is greatly appreciated. Thanks