B737-800
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 133; Flight Crew Type 535
Situational Awareness; Time Pressure
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Human Factors
While enroute to [destination] inside Denver ARTCC airspace; the enroute Controller queried us about our clearance and indicated that we were deviating from what he thought our clearance was. We were at FL370 and in LNAV/VNAV modes with a route of DTA EKR KD63W JALAP. The Controller thought we were DTA EKR FROGS SNY LNK JALAP. He cleared us direct to JALAP without further comment.The dispatched route had a non-standard route and the PDC had an amendment to that route. The PDC amendment changed the SID and first transition point. Though we both reviewed the PDC and the Route page 2; somehow we failed to ensure the correct route was inserted. We accomplished the FMC briefing prior to the Before Start Originating Checklist.We were in the process of an aircraft swap on the last day of a four-day and though the airplane arrived on time; the gate was occupied and we did not board the plane to begin our preflight until 20 minutes prior to scheduled push.I have seen at least three different PDC formats in our MCDUs. I am not a fan of a PDC amendment that is not displayed as a full-route clearance. The partial clearance is confusing. Somehow two pilots incorrectly verified the PDC and entered route. I still don't know how; but I suspect the amended clearance displayed on the PDC in our -800 today contributed to the error.
B737-800 First Officer reported they deviated from cleared track because they failed to see a change to their route in the PDC.