Doug, unfortuneately that is all too common on our cars. First of all the two balancers for the '89 cars were because the Forged crank and Duracast crank were balanced differentely. Check the 8th digit of your VIN, if it is an R you are OK, you have the same Forged steel crank as most of the rest of us. If it is a C you might be out of luck..... maybe a new engine, or a rebuild with a forged crank....
Now the Balancer, I suggest heading over to
www.tbscec.com going to the forums there, go into the FAQ forum , and look for a post by Duffy Floyd titled something like "what is and is not known about the Balancers."
(edit: here is the link
http://pub29.ezboard.com/fthunderbirdscenthusiastclubfrm13.showMessage?topicID=33.topic)
If you look at the stock balancer it has a poor design, it is a steel ring pressed onto an aluminum hub, not a great design. It might be OK for a 'normal' engine, but consider that along with a full load of accessories, this balancer is also transferring power to turn the SUPERCHARGER, which, straight from Eaton, is around 60 HP. So with A/C, power steering, water pump, and the Alternator you are transmitting 75 - 100 HP through that little bit of Aluminum. Also if you ever remove the balancer consider it junk, the aluminum will wear and stretch so it won't fit right again.
Luckily an aftermarket comapny is making New all steel beefy balancers for us, BHJ. They can be expensive, $350 - $400. But it is worth it if you don't ever want your balancer coming apart again. Also Ford has discontinued our Balancer bolt, that you broke, the solution is to get the bolt from a 1999 -2003 Mustang 3.8L They are a bit longer, but work just fine for us.