Muzza, to me it looks like you have the tuneomatic part of a floating bridge for an archtop.
[URL="http://www.realparts.com.au/bridges-tailpieces/arch-top-bridges/gotoh-tunematic-with-rosewood-base.html"]
If that link works, the specs for the TOM are about the same, you just don't have the wooden base.
It's something I came across a while ago when researching bridges for the ES-2V kit.