J1939/ Communication help

[kmk]

I have 2009 Prostar,truck got hit by a lightning. BCM was damaged and replaced with a unit from a donor truck-local dealership network won't have one for another 3 weeks. Truck is running, there is no communication with the ECM(SPN 2000 FMI9), BCM and ABS module communicate. I am able to connect to the engine through the weatherpack connector(private network), Insite reports loss of Data Link. A-com reports Loss of J1939 retarder communication between ECU and EC-60. Ohming out the backbone 58 Ohms, no shorts to ground or power, tried unplugging modules one at a time and checking the resistance on the link, everything checks out. Visually inspected the harnesses and connectors both inside the cab, through the firewall and under the hood, it all looks good. I am leaning towards replacing the ECM, trying to get a known good unit to test the communication, Cummins can not test the ECM. Has anyone had similar experience? Any ideas on testing, I don't want to throw parts at it. Thanks in advance guys.