* Welcome to the Forum.
* You're on the right track. A 42 Code(Mauser), 1939 chamber dated Military P.08. Salt blued with blued small parts & walnut checkered grips. Issued mag would be a blued, folded sheet metal tube bearing an aluminum based plug.
* The right hand side (receiver) eagles should include the left most 2 displaying a stick wing eagle over 63. These are the Army Inspector's acceptance stamps. The right most eagle likely sits atop a circle bearing a swastika within. This is the power proof stamp. This style proof eagle would be the third (late) type of the 3 used by Mauser on military P.08's during the period of 1934-1942.
* Per Jan Still, Third Reich Lugers, about 124,000 Lugers were made in 1939 in at least 3 variations accepted by the Army. Approximately 38,500 were made very early in 1939 & bear a S/42 Mauser Manufacturing code on the middle toggle. The remaining 85,500 pistols were marked with the 1939 chamber date and the "42" toggle code. These latter "42" codes were S/N'd in the range of 200r to 8250z.
* WWII Mauser military P.08's were made in S/N blocks of 10,000 and were differentiated by a lower case suffix letter. Your co-worker's example should display this suffix letter on the frame's vertical surface ahead of the trigger guard and below the barrel. It is an essential part of the S/N of this example. While not intended to assail anyone's gun handling skills, please be absolutely sure the pistol is completely unloaded before checking for this suffix letter. Better to error toward the side of safety; especially, miles apart and in a public Forum setting. Trust you understand & can appreciate.
* All major and numerous (13-14) minor parts are numbered with the full sequence of digits (8314) or a subset of the last 2 numeric digits(14). This includes some internal parts like the firing pin, hold-open, etc. Collector's appeal & pricing are based partially on all matching numbered, original parts.
* Not much more to go on. If you can post pictures, report the suffix block, note other stamps observed(if any), state the magazine particulars, & include any accompanying accessories (holsters, extra mags, etc), we might be able to add to the description already provided.
* Trust this has helped so far.