Putting a modern rear axle in an a body?

all the LX family of cars cam with an IRS rear in them. unless you want to do a ton of fab work it will not be a bolt in deal. and the rears in the LX cars have been known to fail. they will not hold up to much power. (above the factory 5.7 and 6.1 hemi levels) i would say about 100-150 more HP with a sticky tire is about the limit on them.