I've seen them with the curved link bracelet, as on Paul's example:

as well as with flat links:

Could be another example of Heuer offering two different bracelets over a watch's lifetime, they did the same with the barrel Carreras, again one with curved links and one with flat:

The 5100 Carreras had a relatively short life, but Heuer was in such turmoil at the time, we can't rule it out. I had a look at the example Paul has with the curved links and it is a very good fit - I'd say this was the bracelet that was designed for the watch but that the other one matches well enough too and was offered by Heuer. It would need more research to be sure - a price list from that time would be great, as Heuer often included bracelet codes in those and we could check if there were two or if the number changed over time.