Breast Implant Replacement After Surgeon Retired - What Info Do I Need?

It would be preferable to obtain a copy of your medical records. You have a few options. If the surgery was performed at a hospital, you may be able to get the records through the medical records department. If you can recall the manufacturer and in 1996 there were essentially only two: McGhan (=Inamed = Allergan) and Mentor  (now J&J), you may be able to call and see if they have any record of your implants. Sometimes neighboring practices take over the records and I would call around to local practices to ask. They may have some knowledge about who may have your records.
Ultimately, although it is helpful, it is not crucial. You need to review your goals prior to scheduling a consultation with a board certified plastic surgeon:

Do you want to be bigger/smaller?
Do you want to remove them altogether?
Do you want saline or silicone?
Do you want to correct the mild nipple asymmetry with a crescent lift on the right?

In a perfect world, it would be great to have the data: Previous operative report, implant registration with manufacturer, type, style, and size/fill of implant. Unfortunately, we often can not get this information.
We need to start with adressing the main concerns of the patient. What do they not like about their previous result - size change, shape, feel, ripples. Based on the changes we need to attempt to correct one can guide you to where you want to be. Choose an experienced board certified plastic surgeon that you feel comfortable with and talk about your options.