I'm looking at my itin, and it simply says 737-800:
Philadelphia, PA to Salt Lake City, UT
Carrier
Flight # Departs Arrives Equipment
Type Flight
Duration Miles
From Time To Time
Delta 1223 Philadelphia (PHL) 7:00am Salt Lake City (SLC) 10:00am Boeing 737-800 5.00 1926
Total miles: 1926
Given that it's a rather long flight, it would be nice if it was a PTV-equipped aircraft. The route used to be operated with an ex-Song 757, which was very comfortable, and just recently switched to a 738.
Unfortunately, it looks like DL1223 is a regular 738 with overhead/drop-down screens for IFE.. - it's denoted as a "738" in various reservation systems. An aircraft substitution could always happen, I suppose...