: Some 5100 movements were modified to have only two-sub-dials (e.g.
: Silverstone) while some variants of the 5012 were modified for
: three. Can only guess that cost was the main driver, as the 5012
: beats slower than the 5100.

: Some more info here:

: http://www.calibre11.com/heuer-lemania-part-one/
: http://www.calibre11.com/heuer-lemania-part-two/

: David

David,
Many thanks for your reply and for those very informative links. There seems to be very little information about the TAG/Heuer 500.510/12 around, coming as it did at the end of the Heuer "era". I wonder how many other apparently 5100-powered watches there are out there that in fact contain a 3-register 5012 slowly beating away?!
Thanks again

Dave