I found a guy selling a Z for 1500 in craigslist. it has 94k miles on it, but he said a wrist pin is loose and making noise.
1-how do u change it
2- how much
3- I have about 3500 to put to a new car (the 95 v6 was wrecked), would his be a good value?
4- driveable?

see here- http://indianapolis.craigslist.org/cto/1673150978.html

 

$1500 for a 95Z that needs the engine opened is a fair price. I'd drive to be sure the tranny works as well as the HVAC, stereo and inspect the exterior/interior

As for how much$ you are looking at opening the engine if the diagnosis is correct. it may also be a bearing, a rod, a piston slapping etc etc.

Give it a drive, and then price a rebuild. Since you will need to open the motor, you may as well do the right thing to a 100k mile motor.

 

A "loose" wrist pin would mean that it's letting the piston move/rock, and piston slap (hitting the cylinder wall) would be the sound you'd hear. Depends on where the slop is, but you most likely need a new rod, and possibly a new piston if it was damaged/egged out at all.
But....it would be foolish to remove the engine, open it up, and only fix that one problem. With the miles it has, it would make the most amount of sense to rebuild the whole engine, if you plan on making the car a keeper.
Now, if you were getting the car as a fixer-upper to resell, then fixing only what was bad would make the most amount of economical sense.