Which struts are bad? Front or rear? Front are GAS. Rear are AIR.

After 200 miles both are bad , but rear are much worse then the front.

Only 200 miles? Are you sure you installed the correct struts? Have you inspected your stabilizer bar endlink busings also?

the car has 200000 miles on it which is roughly 320000km, and as far as i know no suspension work has been done on it so, also the back end when u push on it hard goes up and down and up agian so I have estimated that the struts are bad thats why i am thinking of replacing them.