A further search on this forum revealed more info about S/M 2570 in the thread 
Chevrolet C60 twins (reposted):
Another survivor in Norway:
	Quote:
	
	
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					Originally Posted by Rolf S. Ask  In a garage nearby he had another C60L (a very original and very nice one)serialnumber 2844321008 which was delivered AUG-6-42 but this one has a SM order number 2570. | 
	
 And info about census numbers:
	Quote:
	
	
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					Originally Posted by David_Hayward (RIP)  L4948501 to 4950228 Contract SM 2570 'LORRY 3 TON 4 X 4 GS ARTICIZED' AS AT 1 OCTOBER 1942: 1,728 PRODUCED | 
	
 HTH,
Hanno