A timeline of LS3/5A manufacture.  Dates are approximate Numbers are approx pairs made
At the time of the re-design in 1987 Rogers continued to use 15 Ohm version labels on the new 11 Ohm units. 
These units are often known as"Pseudo 15 Ohm" had serial numbers in the 31,000 range.
The BBC allowed 3 licences at a time. The exception to this being Harbeth who, under Dudley Harwood held 
a BBC licence from 1977 but did not start manufacture until 1988 under Alan Shaw
Rogers
LS3/5 1974                                      
LS3/5A 1975 15 Ohm Audiomaster
1976   Chartwell 15 Ohm Harbeth
1977   15 Ohm    
1978       RAM  
1979 10,000   15 Ohm  
1980        
1981       Spendor  
1982     15 Ohm  
1983   Goodmans      
1984   15 Ohm    
1985        
1986        
11 Ohm 1987             ?                        
1988 11 Ohm 11 ohm 11 Ohm
1989      
1990 33,500    
Bi-wire 1991                                      
1992       KEF
1993 40,000     11 Ohm
1994      
1995      
1996      
1997      
1998     4000
1999 ? ? ?
2000 Stirling Richard
2001 11 Ohm Allan
2002   11 Ohm
2003    
2004                                     ?
2005 V2
2006  
2007  
2008 New  
2009 LS3/5A  
2010    
2011