Many of the pre X300 Jaguar XJs are listed as "XJ" instead of XJ6. An XJ12 had a 5.3 V12 engine for Series I-III XJs and a 6.0 V12 engine for the XJ40. The XJ12s were the top-of-line versions and considerably rarer than the XJ6s, and people usually call the pre-1994 XJs XJ6s to differentiate them them from the XJ8 which had an all new bodyshell. So how can you tell an XJ12 from an XJ6? Apparently the X300 6 litre V12 had a V12 badge on the pillar, did the earlier models have this?