The Universal Geneve 885103/02 is powered by a standard Valjoux 72, named the Universal Geneve Calibre 85. The only differences between the Cal 85 and the Valjoux 72 are the engraving on the movement. The Cal 85 employs a flat balance spring.
Within the Nina we see a few different engraving designs:
1. On the bridge, UNIVERSAL GENEVE always, with SWISS appearing just below for serials up to 2.45m (roughly above in line with the screw). For most, 85 is engraved below the text and screw, indicating UG Calibre 85. In some cases, 130 is engraved, see bottom of this page for details.
2. On the train gear bridge, engraved is either
a. 17 SEVENTEEN JEWELS UNADJUSTED (top of letters is at case edge). No SWISS.
b. SEVENTEEN, and on the row below, 17 JEWELS (bottom of letters at the case edge). Then UNADJUSTED below the screw, and SWISS above the screw.
I have seen each set of train gear bridge engravings on both early and late serials. Unfortunately, with relatively few movement images (please contact me if you have some!), it is difficult to find a pattern.
About the Universal Geneve Cal 130
I have seen an image of a Cal 130s on one early Universal Geneve 885103/02, though this is not unexpected as the Cal 130 preceded the Cal 85, and we see the Cal 130 appear on the earlier Universal Geneve 885103/01s (“Evil Nina”). Universal Geneve confirms that the Cal 130 was used in some “early” 885103/02 pieces (I take “earlier” to imply a serial of 2.35 or 2.41), with the bridge engraved “130” in the mid-1960s, and “some years later” the 85 bridge . I will include a 885103/02 Cal 130 image when I find one (if you have one, please contact me. The Cal 130 employs a Breguet hairsping.
[image to come]
 Universal Geneve (email April 17, 2020).