Re: 305 zap
I do have one, it came in a box of bits from a retired cyclist. It was new but had been robbed of its bearings I sourced some from Mercian cycles. It's now fitted to my Mercian Audax. Very easy to set up with a concealed bolt that nips up the locking nut and turns as sweet as a nut. Its listed on velobase if that's any help cheers bill