Even living out in Iowa.. seeing full sets of Conrail power (with or without home road leaders) was still common as late as 2001
I've got a shot of an LMS C40-8 paired with a GP38-2 both in NS Patch... on the IC (CN) on a westbound grain train.. around 2001
I also recall seeing a C40/SD60 Trio all in Blue along the Mississippi River on BNSF in 1999 or 2000..
At the same time, there was quite a bit of 2nd hand Blue CR units running around on the IMRL and IANR, along with the LMSX units running on CN.
With all that said...
Per CRCYC..
The 'CSX' SD70MACs were delivered in April 1998 as CR 4130-4144
The 'NS' SD70s were delivered in July-October 1998 as CR 2557-2580
The merger was approved in August 22 1998, and completed in June 1 1999..
As I recall, in that time.. cars allocated to CSXT were reinitialed as NYC..
So.. between Sept 1 1998 and June 1 1999, NYC coal porters should have been increasingly common.
At the same time.. PRR patched locomotives would also be included..