I've recently picked up a nice CS3110 reissue Heuer Carrera, which I wanted to put on a deployant clasp. Fortunately, I had a Heuer branded clasp and a couple of straps that I'd had on other watches of the same size, so ordered up another clasp and we're away... The clasp is part number FC5012 and the official TH strap (which is fitted to the black-faced CS31111, on the right) is part number FC6167. The strap is 18mm at the lug and 16mm at the buckle. When I got the official strap a few years back (from Juergen's in Germany) it was $208 but I then found an aftermarket one which is pretty much the same, for more like £35 IIRC (and that's fitted to the CS3110). There are various compatible 18/16mm straps on http://www.watchbandwarehouse.com/watch-straps/tag-heuer/carrera-18-mm.html The buckle was bought via Ebay but it's also for sale directly from https://watchparts24.de/HEUER-Carrera-deployment-clasp-steel-16mm for €129+ I think this strap/buckle combo looks great - if only I could find a padded 18/16 perforated racing strap in dark blue with white stitching
I have the same combo on mine (in fact there's a thread on it on the forum somewhere!). Agree that a dark blue rally strap would look awesome too.
Highly recommended - I've had my CS3110 on a tang buckle strap for a few weeks and it's just so much nicer on the deployant. Cleaner looking, easier to put on/take off, and I think it sits better on the wrist as well, since the strap holds more of a shape.