I've owned my TAG/Heuer 500.510/12 for a while now but only recently got around to removing the case-back to have a look. I was expecting to find a Lemania 5100 inside, but found the movement is actually a Lemania 5012. I'd never heard of/seen a 3-register 5012 before so I'm intrigued - why this movement in this watch? At the time my TAG/Heuer was made (c1986 I believe) the 5100 was well established and readily available. Why would TAG/Heuer go to the trouble of having a 3-register 5012 made for this watch (and there weren't that many made AFAIK) when the afore-mentioned 5100 was readily available "off-the-shelf"?
I'm also wondering if the Lemania 5012 is unique to the TAG 500.510/12 version of the original Heuer 500.510, or is the movement common to all the 500.510 series?

Checking around the various sections of "On The Dash" hasn't revealed any info regarding movements in this series of Heuer/TAG-Heuer watches so wondering if anyone out there can shed some light on the subject.

Cheers

Dave