I have a 1997 dodge stratus it drives fine but when I make a left or right turn it makes sqeaking noise what could it be.

your sqeek or creeking noise is most likely a dry ball joint ..they stopped putting grease fittings on them and what happens after a while the ball joint pushes what grease that is in there away from one spot and it starts to squeak ....you will have to have some one turn the wheel and have some one listen and hold the ball joint to find out which one it is .....// the only other issue u may have is low fluid in the power steering reservoir....// does it also sqeauk over bumps??

Yes

it says that the upper balljoint can be replaced and pressed int the upper control arm ...// but the lower balljoint comes with the lower control arm...//you just have to figure out which one is the noise one and take it from there

Would it be best to replace both

It only make the most noise when im turning

you can replace both but if one is only making the noise...also it depends on if you are doing it yourself or having a shop do it...you would have to price it out ..napa shows the upper ball joint (A/Arm) for $61.00 and the lower Ball joint( A/ arm) for $164.00....I'm sure if you shop around you may find better prices ...remember a repair shop is gonna mark up the parts