I have a 1951 M38 that has the exact set of numbers on that plate. Mine also had the radio power cable on the jeep when I bought it, so assuming that number references the radio?
Kendall
The radio power cable was standard from Willys on the M38 thru MC47771. The receptacle bracket was standard on all production M38's.
That Federal Stock Class 2740 is not radio equipment. It is a complete vehicle stock class. Most military units updated the Federal Stock Numbers on their vehicle data plates when they were superseded or updated in the stock catalogs. However many did not and many did it on the wrong plate.
58XX is comm & navigation gear
59XX is electronics parts and compents
60XX is antennas, couplers and fiber optics.