CM850 versus CM849

I have searched here and could not find a answer as well as searched on the internet... I am building a 4b cummins and I want it to be a CR engine. Since I work for a company that refurbs diesel generators I have access to a few CM850 cummins ecu. I read one post on here that a gentleman mentioned that he thought the cm849 was the same as the cm850 except the cm849 was for dodge only? Can anyone verify this? I also found where someone said that once a CM850 has a "industrial" "Offroad" program in it that it overwrites some part of the memory and cannot be flashed for a "ON Road" program. Can anyone verify this as well?

That is correct, the CM849 was a Dodge specific ECM, the CM850 uses a totally different CAN protocol.