http://cgi.ebay.com/John-Entwistle-s-1978-Wal-Fretless-Bass-Guitar-/230490243879?cmd=ViewItem&pt=Guitar&hash=item35aa4a0327

Too bad about the string retainer on the peghead ...

Hey Will,
many thanks for the info. But not the thing for me..... :-)
Adriaan, as you can see in the picture with John:
the string retainers were there already when he owned the bass....
Oliver (Spyderman)

I'm doubtful about the Fender-size one under the D&G strings. Originally, it had two small-sized ones like the one still under the E&A strings.