Yamaha SG45 bridge

[Mick Bailey]

I have one of these that someone has badly retrofitted a Tuneomatic bridge and tailpiece. I want to get it back to stock, but can't find a replacement and will probably mill the bridge from brass and plate it. The thing I'm unsure about is how the saddles are constructed and fitted. They appear to straddle a bar that runs the width of the bridge and maybe this is threaded for the adjustment screws.

Has anyone got any further information? - here's how it should look;