As someone said earlier, not all pre-Bs are the same.
Proper pre-Bs take a magazine that is narrower at the top that more recent CZ 75s.
A good place for CZ mags is Greg Cote LLC from Florida. They stock pre-B mags, but they are often out of stock.
There are also some magazines for SP-01s that fit the older pre-Bs. Have a look on the descriptions of what models the magazines fit.
Proper pre-Bs take a magazine that is narrower at the top that more recent CZ 75s.
A good place for CZ mags is Greg Cote LLC from Florida. They stock pre-B mags, but they are often out of stock.
There are also some magazines for SP-01s that fit the older pre-Bs. Have a look on the descriptions of what models the magazines fit.