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			IIUC the HF is an older clunkier design, but still accurate.  The patents on this design apparently have expired so you can copy it cheaply.
		 
		
		
		
		
		
		
			
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				Base 2000 986, beater 1996 Miata, 2011 Suzuki SX4 AWD 
Feline mechanics Condoleezza and Dukie
			 
		
		
		
		
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