I have written the following for several reasons:
1) I could not see any on-line reference to replacing a steering rack for the Lesabre/Olds-88/Bonneville. There are several YouTube videos for other vehicles, but nothing like the H-body.
2) This will give you an appreciation of what you are paying for when you have some one else do it for you. Believe me, the labour is worth it, especially if you're not comfortable working underneath the car.
3) The DIY knows that unexpected difficulties will cause delays and frustration. I've seen mechanics encounter this too. My experience outlined here should prepare you for most of the problems you may encounter, and how to get around them.
Safety note:
If you have done things like ball joints, end links, sub-frame insulators, or other similar suspension related items, you may very well possess the skills to tackle a rack. If you've never done any suspension work before, I'd think twice about the job.
Some cautionary notes:
1) If you are the least bit unsure of how to properly and safely support a unibody car on jack stands, do not attempt this job. You will be spending significant time underneath a car supported on jack stands. People have been injured or killed working underneath an improperly supported car. To make things more complicated, you will be lowering the subframe, adding further dangers.
2) You must be good at following instructions without taking short cuts. One omitted step could compromise the structural integrity of the steering and suspension system. Failure here could cause a serious accident and kill some one. If you haven't already, get a factory service manual for your car. With what you will save in this job, you can afford to get a manual. A Haynes manual may be beneficial, but it does omit several important points that could lead to a failure of the power steering system.