[ARC5] Those Yellow "Serviceable Part" Tags.

[David Stinson]

I have in my collection several  War Department 
A.A.F. Form No. 49 "Serviceable Part" tags
which came on various SCR-183 coils and parts.
These very often have excellent information about the 
aircraft from which it was taken.  
The "W.O." or "Work Order" number is nearly always 
the aircraft's tail number.  
For instance- one here is from tail 42-1238.  
A quick search of the tail number:

From: http://www.aviationarchaeology.com/src/AARmonthly/May1944S.htm
Date 05-13-44
Type BT-13A 
Tail Number 42-12382134
Take-off accident at  Newport AAF. Newport, AR  
Pilot:  Frazier, Henry 
Tagged (assumed salvage date) 5-24-44

From:  http://aviation-safety.net/wikibase/wiki.php?id=120270
Date: 13-MAY-1944
Type: Vultee BT-13A Valiant
Operator: United States Army Air Force (USAAF)
Registration: 42-1238
Airplane damage: Written off (damaged beyond repair)
Location: Newport AAF, Ark    
Phase: Take off
Narrative: Take off accident.

Here's my question:  I thought the tail number preamble 
gave the year of the aircraft's manufacture, i.e. "42-xxxx" 
was built in 1942.   
However, I have a tag here that lists the tail number as
"52-4-45", but a tagging date of  2-4-45.
This tail number seems strange.  Any insights?

73 Dave AB5S