I'm 66 years old, do you think Medicare will pay for a tummy tuck?

I seriously doubt that Medicare will cover the procedure.  Because Medicare doesn’t preauthorize procedures there is no way to know for sure ahead of time.  Therefore your surgeon will expect payment ahead of time.  You can always try billing Medicare but your chances of success are slim.

Dear Ms. Pattistengel, 
 I appreciate how you feel and thank you for your story and questions. Unfortunately with out photos and a exam of your tissues I can can only comment based your story, however I hope you find my comments helpful.Based solely on your story you may benefit from a panneculectomy (removing just the overhanging tissue) than a full abdominoplasty. 
If I understand your question (rephrased: "will insurance cover the costs to make my breasts normal again". And how do I “find” a Plastic Surgeon who will accept my insurance.
Each insurance company covered benefits are a little different how ever most follow the guidelines of the American Medical Association.
Likewise, each physician (despite specialty)make decisions which insurance companies they will contract with based on many factors. 
I have copied directly from the American Medical Association (AMA) 
(1) Our AMA supports the following definitions of "cosmetic" and "reconstructive" surgery: Cosmetic surgery is performed to reshape normal structures of the body in order to improve the patient's appearance and self-esteem. 
Reconstructive surgery is performed on abnormal structures of the body, caused by congenital defects, developmental abnormalities, trauma, infection, tumors or disease. It is generally performed to improve function, but may also be done to approximate a normal appearance.
(2) Our AMA encourages third party payers to use these definitions in determining services eligible for coverage under the plans they offer or administer.(CMS Rep. F, A-89; Reaffirmed: Sunset Report, A-00; Reaffirmed, A-03; Reaffirmed: CMS Rep. 4, A-13).
If you don't qualify you could consider:
1) start a separate savings account (deposit any extra cash or gifts) and watch it grow.
2) ask a different relative (who has good credit scores to counter sign for you)
3)take on a separate job just to add to your separate savings account.
4)Set up “A go fund me account”. 
5)if you live near a University Medical Center, seek out the Plastic Surgery Residents in training. They often discount their services significantly.
6)ask if any in (5) above have seasonal discounts or specials.
Thus, I suggest you  make several appointments with experienced Plastic Surgeons who listens to your specific desires and who are not only Certified by the American Board of Plastic Surgery but in addition ideally a member of the American Society for Aesthetic Plastic Surgery (denoting by membership as having met additional criteria and a focus on Cosmetic Plastic Surgery).
My best wishes,
Dr. R. A. Hardesty, MD, FACS
Diplomate and Certified by the Am. Bd. of Plastic Surgery
Awardee: RealSelf Top 100
wwwimagineplasticsurgery.com
4646 Brockton Ave
Riverside, Ca 92506
(951) 686-7600

Unless there is some unusual circumstance, insurance companies (and Medicare) generally do not cover tummy tuck surgery. In other words, insurance companies do not consider this operation medically necessary. Sometimes, however insurance companies will cover excision of lower abdominal wall skin/apron;  this operation is called a panniculectomy.
The panniculectomy operation involves excision of the lower abdominal wall pannus or  overhanging skin/adipose tissue. It is not considered an  aesthetically driven procedure;  it is often performed to help with concerns such as skin breakdown, infections/rashes… 
Best wishes.