On first glance I would see that as an SP-354 though there are variants without the keep-alive pin (which this one does seem to have). I wonder how it differs from a regular SP-354.
I love these panaplex displays and have used several different types for various clock projects. The SP-354 does not lend itself quite so well to the task with just a leading '1' - there is an SP-151 variant which has the same digits, loses the + and - but gains 'A M P M' and colon parts - I have used those in a couple of designs.
Interesting number variation though.
- Richard