|   Dedicated to the Promotion and Preservation of American Muscle Cars, Dealer built Supercars and COPO cars. | 
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|  COPO Feature 
			
			I have been reading a lot of posts from various  web sites and in almost every instance there is a mention of the proportioning valve on the sub frame being an important feature. Is this a COPO  feature or a BIG block SS feature or did they both have this. When I renewed my brake system I took that system off because fo the condition ofthe valves and when with a more modern system, is this a major issue for value or minor compared to the drive line authenticity??? | 
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