A more complete list is here: http://www.telalink.net/~badger/millist/mi.html
Essentially the number below the Identifier is the contract number (17558). the other numbers indicate it was produced in March of 1945. It may , or may not have been manufactured by Philco, it may have been manufactured by another Philadelphia based manufacturer, but not highly likely.
It is a decent 8 tube reciever, and resale would be what the market would bear. Off the cuff, maybe 30- 50 dollars depending on the collector, maybe more than that depending on how sophisticated it is, as well as condition.
: I have a shortwave radio from WWII. It is painted dark green with a slight wrinkled finnish. The face says "Radio Receiver R-100/URR" and then below this line " 17558-Phila-45-03". Can anyone identify this radio ? Where does it come from, how old, what is it worth ?. Thanks for the info !!