Ultra is always listed as being based in Morteau, as was Altitude, but during my continued research into Ultra I've come across the fact that at one time they also had a workshop in Besançon. According to an employee who worked for Paul Maillardet et Fils (Ultra) at Morteau in the early 1950's, the Usine at Morteau mainly produced the Altitude brand and Besançon the Ultras during this time. The branded Ultra's of that era all seem to have used in-house movements, although later Ultra divers may have not, but Altitude appear to have always used bought in movements.

Altitude had a sub-brand, Mirus, and Ultra produced a range with the face just having the Ultra logo, as well as Ultra Racing and Action, the latter two both with bought in movements. The later Ultra SARL supposedly also produced a watch branded C.I.H. but I think this is doubtful, if you look at some Ultra adverts you can see they describe themselves as a "Compagnie Industrielle Horlogère", a "Watchmaking Industrial Company". There is also the suggestion that Ultra also produced watches branded P Maillardet and Comptoir, but I've not been able to verify these so far.
Ultra produced at least 4 in house movements:
41 (421 etc) 18''',  602 10½''',  703 10½"' Automatic,  904 10½"' SCD.      

The 41 pocket watch movement
The 602 watch movement
The 904 watch movement
I've yet to find images of the 703 automatic nor have I seen an example of the Ultra Superautomatic featuring this movement.

Ultra are one of the few brands to show the movement number on their watch faces, and in any case the 602 can always be recognised by its over sized sub second dial. This is my current 602:

Ultra Racing, with a Parrenin HP60
Ultra's sister company Altitude SARL was based at the Ultra factory at (24?)Rue Fauche in Morteau. At this time Ultra/Altitude had around 250 employees. In the mid 1950's the office had at least 6 shorthand typists, four accounts clerks, six "mécanographes" (?), a translator and an export department. Here's my example of Altitude's production with a Parrenin HP87:

Altitude's only other known brand, Mirus, always seemed to be marked "Fab Altitude", This example features a Parrenin HP90
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Update September 2012

I've now managed to authenticate that Ultra did produce watches branded Paul Maillardet, and I've also seen an Action, finally I've acquired one of another Ultra range, this time an Ultra Prestige, again with a bought in movement, which is in this case a Jeambrun 26D.

I'm still looking out for a decent 904 as well as an automatic, and having now found Racing and Prestige, I'm wondering how just how many other ranges might exist.