You have to drop the tank (if you live in the rust belt, get some new tank
straps BEFORE you start)  The pumps are different between the Vortec(vin
W) and the non-vortec (vin Z).  The fuel pump in your 95 fits 95 only
(seems to be GM's bastard year as a lot of 95 vehicles have 95 only
parts).  If you get it new at a parts store, it should come with the
O-ring for the tank, sometimes they come with a new strainer, if it
doesn't, get one.  I would also replace the fuel filter at that time, too.
Expect to pay between $150-200 for the pump and if you have a shop install
it, expect to pay 2-2.5 hours of labor.  If you do it yourself, make sure
you clean the top of the tank before you open it, the tank seems to
collect a lot of crap on top of it.  It has been my expierence that as
much of a pain in the a.s it is to change, I would not install a used one.