CSX, NS and Conrail are not the only roads that have or had SD40 rebuilt into SD40-2, SP and UP did to, I think UP still have some around. SP were rebuilt at MK like the CSX units.
Not all of them. The 4th order had the HT-C truck. Units 6805 through 6834. Railroads like to keep us modelers on our toes it seems.