Thanks Jeff...but mine is a mixture of newer & older features, according to Hans, with a 57 serial number but a an NY label and long scale. The scale is actually 25 5/8th", and it has slightly rounded-off f/b inlays. It also has a Melita bridge, although there's no way of knowing if that's original. Unfortunately a previous owner applied sticking tape to the underside, which has lifted some of the nitro under the bridge. I don't mind the Melita - it looks somewhat honky, but the plastic saddles mellow out the tone, rather like the old ABR1 plastic saddles did. Useless for string damping, though.
It was bought from Mandolin Bros by a well-know UK jazz guitarist who recorded with it - I subsequently rescued it from fleabay.
The electrics are very robustly done - heavy wire everywhere, huge pots- and still work perfectly. For some odd reason though the Franzes don't have that zig-zag wire on top of the coil, which indicates some internal ''inspection'' in the past. The pickup magnets are very strong after 50+ years - as strong as any current P90 types, and the output voltage from them is the same as a new HB pickup. Makes you wonder about this ''magnet ageing'' thing......
Anyway I'm sitting here typing with the X500 hanging on the wall...I think it's glowing slightly.........