thanx for the reply....
looks like it'll be a stainless.
just an addendum: i plan on scrounging a washer machine pump which is belt driven. taking a garage sale cooler and about 10' of coiled 1/2" copper tubing and pumping rock salt water -7.5 degrees though the chiller via the pump using an old electric motor. a ball valve will be in there somewhere or something like an ols gate valve to adjust flow.
i just remembered today about a 300GPH pond pump that i believe will work out much better than using a washer pump which has to be primed and driven by a seperate motor.
no, i didn't dream it up, but saw this work on you tube under red neck chiller.