I also thought they were mass-air, but I could be wrong too! 
 
Weren't they equipped with 351s?  Those older Lightnings had real 'clean' lines on them. 
 
I would think that it could tow your Mustang without any issues. 
 
E 
		
	
		
		
		
		
		
		
			
				__________________ 
				1991 5.0 LX Coupe - 40,750 miles 
 
331 cu. in. / Tremec 3550 / BFG Drag Radials 
 
12.22 @ 114.31 mph - w/1.89 60'
			 
		
		
		
		
		
		
	
	 |