Just did that about a month ago on my 68 coupe.  Purchased the "Fire Stopper" rear seat to trunk divider from Mustangs Unlimited for $79 (fairly expensive).  It's either 16 or 18-guage steel (can't remember which) and real easy to install.  Painted mine black and it sure beats my original felt. 
		
	
		
		
		
		
		
		
		
		
		
	
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