You are very fortunate.  The only type of rear blades or really any ground engaging implements around here on CL is lightweight stuff.  And then a lot of them are bent or damaged in some manner.  I looked for months for a medium duty box blade of any type and all I found was what I consider to be junk at 75% of new prices.  I ended up purchasing a new Dirt Dog 72" ROBB, 710#.  It works well on my heavy clay, very rocky property and those typical TSC, Agri Supply and most farm store pieces would not have been able to do the job.
	
		
			
		
		
	
				
			 
  
 
		 
 
		 
 
		 
 
		 
 
		 
			 
			 
			 
			 
			