Thanks guys,   i'm not too fussy about diff ratios, but it must be LSD.  I started with the original 3.09 in the atlas but changed last year to a 3.77 when i fitted a bigger turbo to compensate for the increase in lag.  I have over 350 ftlbs and climbing so i dont notice too much difference. 
 
A 3.6 or a 3.9 would be fine. 
 
A dedion wont really fit as the centre of the tube has to sit behind the diff and my fuel tank is fairly close to the live axle as it is. 
I guess i will have to look at getting a book.  The reason i looked at the haynes was because the parts were easily accessible on ebay. 
		
	
		
		
		
		
		
	
		
		
	
	
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