98 Sts Reat Struts Questions

I have a 98 sts. the rear left strut has a rip in the air bag. these struts are very expensive. my question is, if i replace just the ripped one, will it level out the rear end?? also, is it a good idea to just replace the ripped on, or should i replace both?? thanks in advance for the input.

Always better to replace in pairs, money is the consideration here.

thanks