Apologies if this has been covered elsewhere, I am not sure where else to inquire about this and just want to ensure I have the correct information. I've noticed firsthand that the following a/c have BR715-C1-30 written under the tail number placards in the cockpit:

N896AT 9556
N906AT 9582
N935AT 9564
N954AT 9513
N958AT 9517
N963AT 9522
N991AT 9529

Has the entire fleet been upgraded to BR715-C1-30, or just a select few? Does anyone have a list as to which DL 717s have BR715-A1-30 engines and which have BR715-C1-30 engines?

Thanks for your time!