Hellcat USA Numbers and Serial Numbers
Hellcat’s were each designated by a USA Number which was often times painted on the hull of the vehicle. The USA Number was effectively the military “license plate” and for the M18, was keyed off the serial number of the vehicle.
Bill Gross of the GM Museum in Flint Michigan did some research in the archives and discovered that the serial numbers and USA Numbers were sequential. The formula is to simply add 40143876 to the serial number stamped on your Hellcat’s data plate. For example, the serial number of the 40145192 show in the first picture to the left would be serial number 1316, which means it was manufactured in February of 1944.
There were 2,507 M18’s made between July 1943 and October of 1944. Records show how many were produced during each month, and since the serial numbers were sequential, we can produce this simple table:
1943 SN#
July 6
August 89
September 201
October 351
November 618
December 812
1944
January 1062
February 1280
March 1450
April 1600
May 1750
June 1900
July 2050
August 2200
September 2350
October 2507
So, for example, if you had SN# 2036, then it was built in July of 1944.
According to Zaloga’s book, Hellcat’s with serial numbers less or equal to 1350 are considered “early” with the R975-C1 engine. You can usually spot these by noting that the ventilation grill behind the driver is raised, whereas later models they were flat. Compare these two photos and you can see the difference. The photo on the top has a raised vent (just behind the driver’s helmet) which is early, and the late one show below is a flat vent, which has no profile and cannot be seen from the photo. Interestingly enough, the one with the raised grill is SN# 1447, and the one with the flat grill is SN# 1277, which doesn’t match up with this rule.
Also, Zaloga’s research indicates that Hellcat’s with serial numbers greater than or equal to 1858 had a ball-style lock retainer for the main gun, whereas the earlier models did not.
Thursday, May 6, 2010
Where to paint the USA number on a restored Hellcat is a difficult decision, because there was no standard size and/or location as seen in the photographs. Also note that many photos show that the USA Number may have been worn off, overpainted, or was never painted on to begin with.
