This is not a common instrument. Many of these are distributed by Saga under the Regal brand. What brand is yours?
Rather than improvise a new tailpiece, it would be easier to directly contact the manufacturer or distributor. You may have to do this through a local music store. Either way, it will save a lot of time and muttering if you can get the correct part.
I am in need of a 4 string Bass Tailpiece I have a DoBro Bass that the tailpiece broke. Thanks for any help. 
